Family of multi-speed dual-clutch transmissions having three interconnected planetary gear members

ABSTRACT

The family of transmissions has a plurality of members that can be utilized in powertrains to provide at least six forward speed ratios and one reverse speed ratio. The transmission family members include four planetary gear sets, two input clutches, eight torque transmitting mechanisms, and two fixed interconnections. The invention provides a low content multi-speed dual clutch transmission mechanism wherein the two input clutches alternately connect the engine to realize odd and even number speed ratio ranges. The eight torque transmitting mechanisms provide connections between various gear members, the fixed interconnections, the input clutches, the output shaft, and the transmission housing, and are operated in combinations of three to establish at least six forward speed ratios and at least one reverse speed ratio. One of the torque transmitting mechanisms may be eliminated to provide at least five forward speed ratios and at least one reverse speed ratio.

TECHNICAL FIELD

The present invention relates to a family of power transmissions havingtwo input clutches which selectively connect an input shaft to first andsecond pairs of planetary gear sets to provide at least five forwardspeed ratios and one reverse speed ratio.

BACKGROUND OF THE INVENTION

Passenger vehicles include a powertrain that is comprised of an engine,multi-speed transmission, and a differential or final drive. Themulti-speed transmission increases the overall operating range of thevehicle by permitting the engine to operate through its torque range anumber of times.

A primary focus of transmission and engine design work is in the area ofincreasing vehicle fuel efficiency. Manual transmissions typicallyprovide improved vehicle fuel economy over automatic transmissionsbecause automatic transmissions use a torque converter for vehiclelaunch and multiple plate hydraulically-applied clutches for gearengagement. Clutches of this type, left unengaged or idling, impose aparasitic drag torque on a drive line due to the viscous shearing actionwhich exists between the plates and discs rotating at different speedsrelative to one another. This drag torque adversely affects vehicle fueleconomy for automatic transmissions. Also, the hydraulic pump thatgenerates the pressure needed for operating the above-described clutchesfurther reduces fuel efficiency associated with automatic transmissions.Manual transmissions eliminate these problems.

While manual transmissions are not subject to the above described fuelefficiency related problems, manual transmissions typically provide poorshift quality because a significant torque interruption is requiredduring each gear shift as the engine is disengaged from the transmissionby the clutch to allow shafts rotating at different speeds to besynchronized.

So called “automated manual” transmissions provide electronic shiftingin a manual transmission configuration which, in certain circumstances,improves fuel efficiency by eliminating the parasitic losses associatedwith the torque converter and hydraulic pump needed for clutching. Likemanual transmissions, a drawback of automated manual transmissions isthat the shift quality is not as high as an automatic transmissionbecause of the torque interruption during shifting.

So called “dual-clutch automatic” transmissions also eliminate thetorque converter and replace hydraulic clutches with synchronizers butthey go further to provide gear shift quality which is superior to theautomated manual transmission and similar to the conventional automatictransmission, which makes them quite attractive. However, most knowndual-clutch automatic transmissions include a lay shaft or countershaftgear arrangement, and have not been widely applied in vehicles becauseof their complexity, size and cost. For example, a dual clutch lay shafttransmission could require eight sets of gears, two input/shift clutchesand seven synchronizers/dog clutches to provide six forward speed ratiosand a reverse speed ratio. An example of a dual-clutch automatictransmission is described in U.S. Pat. No. 5,385,064, which is herebyincorporated by reference.

SUMMARY OF THE INVENTION

The invention provides a low content multi-speed dual-clutchtransmission family utilizing planetary gear sets rather than lay shaftgear arrangements. In particular, the invention includes four planetarygear sets, two input/shift clutches, and eight selectable torquetransmitting mechanisms to provide at least six forward speed ratios anda reverse speed ratio.

According to one aspect of the invention, the family of transmissionshas four planetary gear sets, each of which includes a first, second andthird member, which members may comprise a sun gear, ring gear, or aplanet carrier assembly member.

In referring to the first, second, third and fourth gear sets in thisdescription and in the claims, these sets may be counted “first” to“fourth” in any order in the drawings (i.e. left-to-right,right-to-left, etc.).

In another aspect of the present invention, each of the planetary gearsets may be of the single pinion type or of the double pinion type.

In yet another aspect of the present invention, the first member of thefirst planetary gear set is continuously connected with the first memberof the second planetary gear set through a first interconnecting member.

In yet another aspect of the present invention, another member of thefirst or second planetary gear set is continuously connected with thefirst member of the third planetary gear set, the first member of thefourth planetary gear set and with the output shaft through a secondinterconnecting member.

In accordance with a further aspect of the invention, a first inputclutch selectively connects the input shaft with a member of the firstor second planetary gear set.

In accordance with another aspect of the present invention, a secondinput clutch selectively connects the input shaft with the second memberof the third planetary gear set.

In another aspect of the invention, first and second torque transmittingmechanisms, such as synchronizers, selectively connect members of thefirst and second planetary gear sets with other members of the first andsecond planetary gear sets, or with the first input clutch.

In still a further aspect of the invention, third and fourth torquetransmitting mechanisms, such as synchronizers, selectively connectmembers of the third planetary gear set with members of the fourthplanetary gear set.

In still another aspect of the invention, fifth and sixth torquetransmitting mechanisms, such as brakes, selectively connect members ofthe first or second planetary gear set with a stationary member(transmission housing).

In still another aspect of the invention, seventh and eighth torquetransmitting mechanisms, such as brakes, selectively connect members ofthe fourth planetary gear set with the stationary member.

In accordance with a further aspect of the invention, the input clutchesand torque transmitting mechanisms are selectively engaged incombinations of at least three to provide at least six forward speedratios and a reverse speed ratio.

In accordance with a further aspect of the invention, the eight torquetransmitting mechanisms may comprise synchronizers.

In accordance with a further aspect of the invention, the first inputclutch is applied for odd number speed ranges, and the second inputclutch is applied for even number speed ranges, or vice versa.

In another aspect of the invention, the first input clutch and thesecond input clutch are interchanged (i.e. alternately engaged) to shiftfrom odd number speed range to even number speed range, or vice versa.

In accordance with a further aspect of the invention, each selectedtorque transmitting mechanism for a new speed ratio is engaged prior toshifting of the input clutches to achieve shifts without torqueinterruptions.

In accordance with a further aspect of the invention, at least one pairof synchronizers is executed as a double synchronizer to reduce cost andpackage size.

In accordance with a further aspect of the invention, at least one ofthe torque transmitting mechanisms can be eliminated to realize fiveforward speed ratios and a reverse speed ratio.

The above objects, features, advantages, and other objects, features,and advantages of the present invention are readily apparent from thefollowing detailed description of the best modes for carrying out theinvention when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a schematic representation of a powertrain including aplanetary transmission incorporating a family member of the presentinvention;

FIG. 1b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 1a;

FIG. 2a is a schematic representation of a powertrain having a planetarytransmission incorporating another family member of the presentinvention;

FIG. 2b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 2a;

FIG. 3a is a schematic representation of a powertrain having a planetarytransmission incorporating another family member of the presentinvention;

FIG. 3b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 3a;

FIG. 4a is a schematic representation of a powertrain having a planetarytransmission incorporating another family member of the presentinvention;

FIG. 4b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 4a;

FIG. 5a is a schematic representation of a powertrain having a planetarytransmission incorporating another family member of the presentinvention;

FIG. 5b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 5a;

FIG. 6a is a schematic representation of a powertrain having a planetarytransmission incorporating another family member of the presentinvention;

FIG. 6b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 6a;

FIG. 7a is a schematic representation of a powertrain having a planetarytransmission incorporating another family member of the presentinvention;

FIG. 7b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 7a;

FIG. 8a is a schematic representation of a powertrain having a planetarytransmission incorporating another family member of the presentinvention;

FIG. 8b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 8a;

FIG. 9a is a schematic representation of a powertrain having a planetarytransmission incorporating another family member of the presentinvention;

FIG. 9b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 9a;

FIG. 10a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 10b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 10a;

FIG. 11a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 11b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 11a;

FIG. 12a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 12b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 12a;

FIG. 13a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 13b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 13a;

FIG. 14a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention; and

FIG. 14b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 14a.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, wherein like characters represent the same orcorresponding parts throughout the several views, there is shown in FIG.1a a powertrain 10 having a conventional engine 12, a planetarytransmission 14, and a conventional final drive mechanism 16.

The planetary transmission 14 includes an input shaft 17 continuouslyconnected with the engine 12, a planetary gear arrangement 18, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 18 includes four planetary gear sets20, 30, 40 and 50.

The planetary gear set 20 includes a sun gear member 22, a ring gearmember 24, and a planet carrier assembly member 26. The planet carrierassembly member 26 includes a plurality of pinion gears 27 rotatablymounted on a carrier member 29 and disposed in meshing relationship withboth the sun gear member 22 and the ring gear member 24.

The planetary gear set 30 includes a sun gear member 32, a ring gearmember 34, and a planet carrier assembly member 36. The planet carrierassembly member 36 includes a plurality of pinion gears 37 rotatablymounted on a carrier member 39 and disposed in meshing relationship withboth the sun gear member 32 and the ring gear member 34.

The planetary gear set 40 includes a sun gear member 42, a ring gearmember 44, and a planet carrier assembly member 46. The planet carrierassembly member 46 includes a plurality of pinion gears 47 rotatablymounted on a carrier member 49 and disposed in meshing relationship withboth the sun gear member 42 and the ring gear member 44.

The planetary gear set 50 includes a sun gear member 52, a ring gearmember 54, and a planet carrier assembly member 56. The planet carrierassembly member 56 includes a plurality of pinion gears 57 rotatablymounted on a carrier member 59 and disposed in meshing relationship withboth the sun gear member 52 and the ring gear member 54.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 20, 30, 40 and 50 are divided into first and secondtransmission subsets 60, 61 which are alternatively engaged to provideodd number and even number speed ranges, respectively. Transmissionsubset 60 includes planetary gear sets 20 and 30, and transmissionsubset 61 includes planetary gear sets 40 and 50. The output shaft 19 iscontinuously connected with members of both subsets 60 and 61.

As mentioned above, the first and second input clutches 62, 63 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 60 or transmission subset 61. The first and secondinput clutches 62, 63 are controlled electronically, and the disengagedinput clutch is gradually engaged while the engaged input clutch isgradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 60, 61 prior to engaging therespective input clutches 62, 63. The preselection is achieved by meansof electronically controlled synchronizers. As shown, the planetary geararrangement includes eight torque transmitting mechanisms 64, 65, 66,67, 68, 69, 70 and 71. The torque transmitting mechanisms 64, 65, 68 and69 comprise braking synchronizers, and the torque transmittingmechanisms 66, 67, 70 and 71 comprise rotating synchronizers.

The rotating synchronizers and braking synchronizers are referred to inthe claims as follows: first and second torque transmitting mechanisms66, 67; third and fourth torque transmitting mechanisms 70, 71; fifthand sixth torque transmitting mechanisms 64, 65; and seventh and eighthtorque transmitting mechanisms 68, 69. The other family members aresimilarly referenced in the claims (i.e. rotating synchronizersgenerally in order of planetary gear sets from left to right in Figures;and braking synchronizers generally in order of planetary gear sets fromleft to right in Figures).

By way of example, synchronizers which may be implemented as therotating and/or braking synchronizers referenced herein are shown in thefollowing patents, each of which are incorporated by reference in theirentirety: U.S. Pat. Nos. 5,651,435; 5,975,263; 5,560,461; 5,641,045;5,497,867; 6,354,416.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 60, 61 (i.e. through the clutch 62 tothe sun gear member 22 and through the clutch 63 to the sun gear member42). The ring gear member 24 is continuously connected with the sun gearmember 32 through the interconnecting member 72. The planet carrierassembly member 36 is continuously connected with the planet carrierassembly member 46, the sun gear member 54 and the output shaft 19through the interconnecting member 74.

The sun gear member 22 is selectively connectable with the input shaft17 through the input clutch 62. The sun gear member 42 is selectivelyconnectable with the input shaft 17 through the input clutch 63. The sungear member 24 is selectively connectable with the transmission housing80 through the braking synchronizer 64. The planet carrier assemblymember 26 is selectively connectable with the transmission housing 80through the braking synchronizer 65. The planet carrier assembly member26 is selectively connectable with the ring gear member 34 through thesynchronizer 66. The ring gear member 34 is selectively connectable withthe sun gear member 22 through the synchronizer 67. The planet carrierassembly member 56 is selectively connectable with the transmissionhousing 80 through the braking synchronizer 68. The sun gear member 52is selectively connectable with the transmission housing 80 through thebraking synchronizer 69. The ring gear member 44 is selectivelyconnectable with the planet carrier assembly member 56 through thesynchronizer 70. The ring gear member 44 is selectively connectable withthe sun gear member 52 through the synchronizer 71.

As shown in FIG. 1b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio.

The reverse speed ratio is established with the engagement of the inputclutch 62, the braking synchronizer 65 and the synchronizer 66. Theinput clutch 62 connects the sun gear member 22 to the input shaft 17.The braking synchronizer 65 connects the planet carrier assembly member26 to the transmission housing 80. The synchronizer 66 connects theplanet carrier assembly member 26 to the ring gear member 34. The sungear member 22 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 26 and the ring gear member 34 do notrotate. The ring gear member 24 rotates at the same speed as the sungear member 32. The ring gear member 24 rotates at a speed determinedfrom the speed of the sun gear member 22 and the ring gear/sun geartooth ratio of the planetary gear set 20. The planet carrier assemblymember 36 and the planet carrier assembly member 46 rotate at the samespeed as the output shaft 19. The planet carrier assembly member 36, andtherefore the output shaft 19, rotates at a speed determined from thespeed of the sun gear member 32 and the ring gear/sun gear tooth ratioof the planetary gear set 30. The numerical value of the reverse speedratio is determined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 20, 30.

The first forward speed ratio is established with the engagement of theinput clutch 63, the braking synchronizer 68 and the synchronizer 71.The input clutch 63 connects the sun gear member 42 to the input shaft17. The braking synchronizer 68 connects the planet carrier assemblymember 56 to the transmission housing 80. The synchronizer 71 connectsthe ring gear member 44 to the sun gear member 52. The sun gear member42 rotates at the same speed as the input shaft 17. The planet carrierassembly member 46 and the ring gear member 54 rotate at the same speedas the output shaft 19. The ring gear member 44 rotates at the samespeed as the sun gear member 52. The planet carrier assembly member 46,and therefore the output shaft 19, rotates at a speed determined fromthe speed of the ring gear member 44, the speed of the sun gear member42 and the ring gear/sun gear tooth ratio of the planetary gear set 40.The planet carrier assembly member 56 does not rotate. The ring gearmember 54 rotates at a speed determined from the speed of the sun gearmember 52 and the ring gear/sun gear tooth ratio of the planetary gearset 50. The numerical value of the first forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 40, 50.

The second forward speed ratio is established with the engagement of theinput clutch 62, the braking synchronizer 64 and the synchronizer 66.The input clutch 62 connects the sun gear member 22 to the input shaft17. The braking synchronizer 64 connects the ring gear member 24 to thetransmission housing 80. The synchronizer 66 connects the ring gearmember 34 to the planet carrier assembly member 26. The sun gear member22 rotates at the same speed as the input shaft 17. The planet carrierassembly member 26 rotates at the same speed as the ring gear member 34.The ring gear member 24 and the sun gear member 32 do not rotate. Theplanet carrier assembly member 26 rotates at a speed determined from thespeed of the sun gear member 22 and the ring gear/sun gear tooth ratioof the planetary gear set 20. The planet carrier assembly member 36 andthe planet carrier assembly member 46 rotate at the same speed as theoutput shaft 19. The planet carrier assembly member 36, and thereforethe output shaft 19, rotates at a speed determined from the speed of thering gear member 34 and the ring gear/sun gear tooth ratio of theplanetary gear set 30. The numerical value of the second forward speedratio is determined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 20, 30.

The third forward speed ratio is established with the engagement of theinput clutch 63, the braking synchronizer 68 and the synchronizer 70.The input clutch 63 connects the sun gear member 42 to the input shaft17. The braking synchronizer 68 connects the planet carrier assemblymember 56 to the transmission housing 80. The synchronizer 70 connectsthe ring gear member 44 to the planet carrier assembly member 56. Thesun gear member 42 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 46 and the ring gear member 54 rotate atthe same speed as the output shaft 19. The ring gear member 44 and theplanet carrier assembly member 56 do not rotate. The planet carrierassembly member 46, and therefore the output shaft 19, rotates at aspeed determined from the speed of the sun gear member 42 and the ringgear/sun gear tooth ratio of the planetary gear set 40. The numericalvalue of the third forward speed ratio is determined utilizing the ringgear/sun gear tooth ratio of the planetary gear set 40.

The fourth forward speed ratio is established with the engagement of theinput clutch 62, the braking synchronizer 65 and the synchronizer 67.The input clutch 62 connects the sun gear member 22 to the input shaft17. The braking synchronizer 65 connects the planet carrier assemblymember 26 to the transmission housing 80. The synchronizer 67 connectsthe sun gear member 22 to the ring gear member 34. The sun gear member22 and the ring gear member 34 rotate at the same speed as the inputshaft 17. The planet carrier assembly member 26 does not rotate. Thering gear member 24 rotates at the same speed as the sun gear member 32.The ring gear member 24 rotates at a speed determined from the speed ofthe sun gear member 22 and the ring gear/sun gear tooth ratio of theplanetary gear set 20. The planet carrier assembly member 36 and theplanet carrier assembly member 46 rotate at the same speed as the outputshaft 19. The planet carrier assembly member 36, and therefore theoutput shaft 19, rotates at a speed determined from the speed of thering gear member 34, the speed of the sun gear member 32 and the ringgear/sun gear tooth ratio of the planetary gear set 30. The numericalvalue of the fourth forward speed ratio is determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 20, 30.

The fifth forward speed ratio is established with the engagement of theinput clutch 63, the braking synchronizer 69 and the synchronizer 70.The input clutch 63 connects the sun gear member 42 to the input shaft17. The braking synchronizer 69 connects the sun gear member 52 to thetransmission housing 80. The synchronizer 70 connects the ring gearmember 44 to the planet carrier assembly member 56. The sun gear member42 rotates at the same speed as the input shaft 17. The planet carrierassembly member 46 and the ring gear member 54 rotate at the same speedas the output shaft 19. The ring gear member 44 rotates at the samespeed as the planet carrier assembly member 56. The planet carrierassembly member 46, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 44, the speed ofthe sun gear member 42 and the ring gear/sun gear tooth ratio of theplanetary gear set 40. The sun gear member 52 does not rotate. The ringgear member 54 rotates at a speed determined from the speed of theplanet carrier assembly member 56 and the ring gear/sun gear tooth ratioof the planetary gear set 50. The numerical value of the fifth forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 40, 50.

The sixth forward speed ratio is established with the engagement of theinput clutch 62, and the synchronizers 66, 67. In this configuration,the input shaft 17 is directly connected to the output shaft 19. Thenumerical value of the sixth forward speed ratio is 1.

As set forth above, the engagement schedule for the torque transmittingmechanisms is shown in the truth table of FIG. 1b. This truth table alsoprovides an example of speed ratios that are available utilizing thering gear/sun gear tooth ratios given by way of example in FIG. 1b. TheR1/S1 value is the tooth ratio of the planetary gear set 20; the R2/S2value is the tooth ratio of the planetary gear set 30; the R3/S3 valueis the tooth ratio of the planetary gear set 40; and the R4/S4 value isthe tooth ratio of the planetary gear set 50. Also, the chart of FIG. 1bdescribes the ratio steps that are attained utilizing the sample oftooth ratios given. For example, the step ratio between first and secondforward speed ratios is 1.76, while the step ratio between the reverseand first forward ratio is −0.76.

FIG. 2a shows a powertrain 110 having a conventional engine 12, aplanetary transmission 114, and a conventional final drive mechanism 16.The planetary transmission 114 includes an input shaft 17 connected withthe engine 12, a planetary gear arrangement 118, and an output shaft 19connected with the final drive mechanism 16. The planetary geararrangement 118 includes four planetary gear sets 120, 130, 140 and 150.

The planetary gear set 120 includes a sun gear member 122, a ring gearmember 124, and a planet carrier assembly member 126. The planet carrierassembly member 126 includes a plurality of pinion gears 127 rotatablymounted on a carrier member 129 and disposed in meshing relationshipwith both the sun gear member 122 and the ring gear member 124.

The planetary gear set 130 includes a sun gear member 132, a ring gearmember 134, and a planet carrier assembly member 136. The planet carrierassembly member 136 includes a plurality of intermeshing pinion gears137, 138 rotatably mounted on a carrier member 139 and disposed inmeshing relationship with the ring gear member 134 and the sun gearmember 132, respectively.

The planetary gear set 140 includes a sun gear member 142, a ring gearmember 144, and a planet carrier assembly member 146. The planet carrierassembly member 146 includes a plurality of pinion gears 147 rotatablymounted on a carrier member 149 and disposed in meshing relationshipwith both the sun gear member 142 and the ring gear member 144.

The planetary gear set 150 includes a sun gear member 152, a ring gearmember 154, and a planet carrier assembly member 156. The planet carrierassembly member 156 includes a plurality of pinion gears 157 rotatablymounted on a carrier member 159 and disposed in meshing relationshipwith both the sun gear member 152 and the ring gear member 154.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 120, 130, 140 and 150 are divided into first andsecond transmission subsets 160, 161 which are alternatively engaged toprovide odd number and even number speed ranges, respectively.Transmission subset 160 includes planetary gear sets 120 and 130, andtransmission subset 161 includes planetary gear sets 140 and 150. Theoutput shaft 19 is continuously connected with members of both subsets160 and 161.

As mentioned above, the first and second input clutches 162, 163 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 160 or transmission subset 161. The first and secondinput clutches 162, 163 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 160, 161 prior to engagingthe respective input clutches 162, 163. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms164, 165, 166, 167, 168, 169, 170 and 171. The torque transmittingmechanisms 164, 165, 168 and 169 comprise braking synchronizers, and thetorque transmitting mechanisms 166, 167, 170 and 171 comprise rotatingsynchronizers.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 160, 161 (i.e. through the clutch 162 tothe sun gear member 122 and through the clutch 163 to the sun gearmember 142). The planet carrier assembly member 126 is continuouslyconnected with the sun gear member 132 through the interconnectingmember 172. The ring gear member 134 is continuously connected with theplanet carrier assembly member 146, the ring gear member 154 and theoutput shaft 19 through the interconnecting member 174.

The sun gear member 122 is selectively connectable with the input shaft17 through the input clutch 162. The sun gear member 142 is selectivelyconnectable with the input shaft 17 through the input clutch 163. Theplanet carrier assembly member 126 is selectively connectable with thetransmission housing 180 through the braking synchronizer 164. The ringgear member 124 is selectively connectable with the transmission housing180 through the braking synchronizer 165. The ring gear member 124 isselectively connectable with the planet carrier assembly member 136through the synchronizer 166. The sun gear member 122 is selectivelyconnectable with the planet carrier assembly member 136 through thesynchronizer 167. The planet carrier assembly member 156 is selectivelyconnectable with the transmission housing 180 through the brakingsynchronizer 168. The sun gear member 152 is selectively connectablewith the transmission housing 180 through the braking synchronizer 169.The ring gear member 144 is selectively connectable with the planetcarrier assembly member 156 through the synchronizer 170. The ring gearmember 144 is selectively connectable with the sun gear member 152through the synchronizer 171.

As shown in FIG. 2b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio.

The reverse speed ratio is established with the engagement of the inputclutch 162, the braking synchronizer 164 and the synchronizer 166. Theinput clutch 162 connects the sun gear member 122 to the input shaft 17.The braking synchronizer 164 connects the planet carrier assembly member126 to the transmission housing 180. The synchronizer 166 connects thering gear member 124 to the planet carrier assembly member 136. The sungear member 122 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 126 and the sun gear member 132 do notrotate. The ring gear member 124 rotates at the same speed as the planetcarrier assembly member 136. The ring gear member 124 rotates at a speeddetermined from the speed of the sun gear member 122 and the ringgear/sun gear tooth ratio of the planetary gear set 120. The ring gearmember 134 and the planet carrier assembly member 146 rotate at the samespeed as the output shaft 19. The ring gear member 134, and thereforethe output shaft 19, rotates at a speed determined from the speed of theplanet carrier assembly member 136 and the ring gear/sun gear toothratio of the planetary gear set 130. The numerical value of the reversespeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear set 120, 130.

The first forward speed ratio is established with the engagement of theinput clutch 163, the braking synchronizer 168 and the synchronizer 171.The input clutch 163 connects the sun gear member 142 to the input shaft17. The braking synchronizer 168 connects the planet carrier assemblymember 156 to the transmission housing 180. The synchronizer 171connects the ring gear member 144 to the sun gear member 152. The sungear member 142 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 146 and the ring gear member 154 rotateat the same speed as the output shaft 19. The ring gear member 144rotates at the same speed as the sun gear member 152. The planet carrierassembly member 146, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 144, the speedof the sun gear member 142 and the ring gear/sun gear tooth ratio of theplanetary gear set 140. The planet carrier assembly member 156 does notrotate. The ring gear member 154 rotates at a speed determined from thespeed of the sun gear member 152 and the ring gear/sun gear tooth ratioof the planetary gear set 150. The numerical value of the first forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear set 140, 150.

The second forward speed ratio is established with the engagement of theinput clutch 162, the braking synchronizer 165 and the synchronizer 166.The input clutch 162 connects the sun gear member 122 to the input shaft17. The braking synchronizer 165 connects the ring gear member 124 tothe transmission housing 180. The synchronizer 166 connects the ringgear member 124 to the planet carrier assembly member 136. The sun gearmember 122 rotates at the same speed as the input shaft 17. The planetcarrier assembly member 126 rotates at the same speed as the sun gearmember 132. The sun gear member 124 and the planet carrier assemblymember 136 do not rotate. The planet carrier assembly member 126 rotatesat a speed determined from the speed of the sun gear member 122 and thering gear/sun gear tooth ratio of the planetary gear set 120. The ringgear member 134 and the planet carrier assembly member 146 rotate at thesame speed as the output shaft 19. The ring gear member 134, andtherefore the output shaft 19, rotates at a speed determined from thespeed of the sun gear member 132 and the ring gear/sun gear tooth ratioof the planetary gear set 130. The numerical value of the second forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 120, 130.

The third forward speed ratio is established with the engagement of theinput clutch 163, the braking synchronizer 168 and the synchronizer 170.The input clutch 163 connects the sun gear member 142 to the input shaft17. The braking synchronizer 168 connects the planet carrier assemblymember 156 to the transmission housing 180. The synchronizer 170connects the ring gear member 144 to the planet carrier assembly member156. The sun gear member 142 rotates at the same speed as the inputshaft 17. The planet carrier assembly member 146 and the ring gearmember 154 rotate at the same speed as the output shaft 19. The ringgear member 144 and the planet carrier assembly member 156 do notrotate. The planet carrier assembly member 146, and therefore the outputshaft 19, rotates at a speed determined from the speed of the sun gearmember 142 and the ring gear/sun gear tooth ratio of the planetary gearset 140. The numerical value of the third forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratio of the planetarygear set 140.

The fourth forward speed ratio is established with the engagement of theinput clutch 162, the braking synchronizer 165 and the synchronizer 167.The input clutch 162 connects the sun gear member 122 to the input shaft17. The braking synchronizer 165 connects the ring gear member 124 tothe transmission housing 180. The synchronizer 167 connects the sun gearmember 122 to the planet carrier assembly member 136. The sun gearmember 122 and the planet carrier assembly member 136 rotate at the samespeed as the input shaft 17. The planet carrier assembly member 126rotates at the same speed as the sun gear member 132. The ring gearmember 124 does not rotate. The planet carrier assembly member 126rotates at a speed determined from the speed of the sun gear member 122and the ring gear/sun gear tooth ratio of the planetary gear set 120.The ring gear member 134 and the planet carrier assembly member 146rotate at the same speed as the output shaft 19. The ring gear member134, and therefore the output shaft 19, rotates at a speed determinedfrom the speed of the planet carrier assembly member 136, the speed ofthe sun gear member 132 and the ring gear/sun gear tooth ratio of theplanetary gear set 130. The numerical value of the fourth forward speedratio is determined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 120, 130.

The fifth forward speed ratio is established with the engagement of theinput clutch 163, the braking synchronizer 169 and the synchronizer 170.The input clutch 163 connects the sun gear member 142 to the input shaft17. The braking synchronizer 169 connects the sun gear member 152 to thetransmission housing 180. The synchronizer 170 connects the ring gearmember 144 to the planet carrier assembly member 156. The sun gearmember 142 rotates at the same speed as the input shaft 17. The planetcarrier assembly member 146 and the ring gear member 154 rotate at thesame speed as the output shaft 19. The ring gear member 144 rotates atthe same speed as the planet carrier assembly member 156. The planetcarrier assembly member 146, and therefore the output shaft 19, rotatesat a speed determined from the speed of the ring gear member 144, thespeed of the sun gear member 142 and the ring gear/sun gear tooth ratioof the planetary gear set 140. The sun gear member 152 does not rotate.The ring gear member 154 rotates at a speed determined from the speed ofthe planet carrier assembly member 156 and the ring gear/sun gear toothratio of the planetary gear set 150. The numerical value of the fifthforward speed ratio is determined utilizing the ring gear/sun gear toothratios of the planetary gear sets 140, 150.

The sixth forward speed ratio is established with the engagement of theinput clutch 162, and the synchronizers 166, 167. In this configuration,the input shaft 17 is directly connected to the output shaft 19. Thenumerical value of the sixth forward speed ratio is 1.

As set forth above, the truth table of FIG. 2b describes the engagementsequence of the torque transmitting mechanisms utilized to provide areverse drive ratio and six forward speed ratios. The truth table alsoprovides an example of the ratios that can be attained with the familymembers shown in FIG. 2a utilizing the sample tooth ratios given in FIG.2b. The R1/S1 value is the tooth ratio of the planetary gear set 120;the R2/S2 value is the tooth ratio of the planetary gear set 130; theR3/S3 value is the tooth ratio of the planetary gear set 140; and theR4/S4 value is the tooth ratio of the planetary gear set 150. Also shownin FIG. 2b are the ratio steps between single step ratios in the forwarddirection as well as the reverse to first ratio step. For example, thefirst to second step ratio is 1.73.

Turning the FIG. 3a, a powertrain 210 having a conventional engine 12, aplanetary transmission 214, and conventional final drive mechanism 16 isshown.

The planetary transmission 214 includes an input shaft 17 continuouslyconnected with the engine 12, a planetary gear arrangement 218, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 218 includes four planetary gear sets220, 230, 240 and 250.

The planetary gear set 220 includes a sun gear member 222, a ring gearmember 224, and a planet carrier assembly member 226. The planet carrierassembly member 226 includes a plurality of pinion gears 227 rotatablymounted on a carrier member 229 and disposed in meshing relationshipwith both the sun gear member 222 and the ring gear member 224.

The planetary gear set 230 includes a sun gear member 232, a ring gearmember 234, and a planet carrier assembly member 236. The planet carrierassembly member 236 includes a plurality of pinion gears 237 rotatablymounted on a carrier member 239 and disposed in meshing relationshipwith both the sun gear member 232 and the ring gear member 234.

The planetary gear set 240 includes a sun gear member 242, a ring gearmember 244, and a planet carrier assembly member 246. The planet carrierassembly member 246 includes a plurality of pinion gears 247 rotatablymounted on a carrier member 249 and disposed in meshing relationshipwith both the sun gear member 242 and the ring gear member 244.

The planetary gear set 250 includes a sun gear member 252, a ring gearmember 254, and a planet carrier assembly member 256. The planet carrierassembly member 256 includes a plurality of pinion gears 257 rotatablymounted on a carrier member 259 and disposed in meshing relationshipwith both the sun gear member 252 and the ring gear member 254.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 220, 230, 240 and 250 are divided into first andsecond transmission subsets 260, 261 which are alternatively engaged toprovide odd number and even number speed ranges, respectively.Transmission subset 260 includes planetary gear sets 220 and 230, andtransmission subset 261 includes planetary gear sets 240 and 250. Theoutput shaft 19 is continuously connected with members of both subsets260 and 261.

As mentioned above, the first and second input clutches 262, 263 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 260 or transmission subset 261. The first and secondinput clutches 262, 263 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 260, 261 prior to engagingthe respective input clutches 262, 263. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms264, 265, 266, 267, 268, 269, 270 and 271. The torque transmittingmechanisms 264, 265, 268 and 269 comprise braking synchronizers, and thetorque transmitting mechanisms 266, 267, 270 and 271 comprise rotatingsynchronizers.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 260, 261 (i.e. through the clutch 262 tothe sun gear member 222 and through the clutch 263 to the sun gearmember 242). The ring gear member 224 is continuously connected with thesun gear member 232 through the interconnecting member 272. The planetcarrier assembly member 236 is continuously connected with the planetcarrier assembly member 246, the ring gear member 254 and the outputshaft 19 through the interconnecting member 274.

The sun gear member 222 is selectively connectable with the input shaft17 through the input clutch 262. The sun gear member 242 is selectivelyconnectable with the input shaft 17 through the input clutch 263. Thering gear member 224 is selectively connectable with the transmissionhousing 280 through the braking synchronizer 264. The planet carrierassembly member 226 is selectively connectable with the transmissionhousing 280 through the braking synchronizer 265. The sun gear member222 is selectively connectable with the ring gear member 234 through thesynchronizer 266. The planet carrier assembly member 226 is selectivelyconnectable with the ring gear member 234 through the synchronizer 267.The planet carrier assembly member 256 is selectively connectable withthe transmission housing 280 through the braking synchronizer 268. Thesun gear member 252 is selectively connectable with the transmissionhousing 280 through the braking synchronizer 269. The ring gear member244 is selectively connectable with the planet carrier assembly member256 through the synchronizer 270. The ring gear member 244 isselectively connectable with the sun gear member 252 through thesynchronizer 271.

As shown in FIG. 3b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio.

The reverse speed ratio is established with the engagement of the inputclutch 262, the braking synchronizer 265 and the synchronizer 267. Theinput clutch 262 connects the sun gear member 222 to the input shaft 17.The braking synchronizer 265 connects the planet carrier assembly member226 to the transmission housing 280. The synchronizer 267 connects theplanet carrier assembly member 226 to the ring gear member 234. The sungear member 222 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 226 and the ring gear member 234 do notrotate. The ring gear member 224 rotates at the same speed as the sungear member 232. The ring gear member 224 rotates at a speed determinedfrom the speed of the sun gear member 222 and the ring gear/sun geartooth ratio of the planetary gear set 220. The planet carrier assemblymember 236 and the planet carrier assembly member 246 rotate at the samespeed as the output shaft 19. The planet carrier assembly member 236,and therefore the output shaft 19, rotates at a speed determined fromthe speed of the sun gear member 232 and the ring gear/sun gear toothratio of the planetary gear set 230. The numerical value of the reversespeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 220, 230.

The first forward speed ratio is established with the engagement of theinput clutch 263, the braking synchronizer 268 and the synchronizer 271.The input clutch 263 connects the sun gear member 242 to the input shaft17. The braking synchronizer 268 connects the planet carrier assemblymember 256 to the transmission housing 280. The synchronizer 271connects the ring gear member 244 to the sun gear member 252. The sungear member 242 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 246 and the ring gear member 254 rotateat the same speed as the output shaft 19. The ring gear member 244rotates at the same speed as the sun gear member 252. The planet carrierassembly member 246, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 244, the speedof the sun gear member 242 and the ring gear/sun gear tooth ratio of theplanetary gear set 240. The planet carrier assembly member 256 does notrotate. The ring gear member 254 rotates at a speed determined from thespeed of the sun gear member 252 and the ring gear/sun gear tooth ratioof the planetary gear set 250. The numerical value of the first forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 240, 250.

The second forward speed ratio is established with the engagement of theinput clutch 262, the braking synchronizer 264 and the synchronizer 267.The input clutch 262 connects the sun gear member 222 to the input shaft17. The braking synchronizer 264 connects the ring gear member 224 tothe transmission housing 280. The synchronizer 267 connects the planetcarrier assembly member 226 to the ring gear member 234. The sun gearmember 222 rotates at the same speed as the input shaft 17. The planetcarrier assembly member 226 rotates at the same speed as the ring gearmember 234. The ring gear member 224 and the sun gear member 232 do notrotate. The planet carrier assembly member 226 rotates at a speeddetermined from the speed of the sun gear member 222 and the ringgear/sun gear tooth ratio of the planetary gear set 220. The planetcarrier assembly member 236 and the planet carrier assembly member 246rotate at the same speed as the output shaft 19. The planet carrierassembly member 236, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 234 and the ringgear/sun gear tooth ratio of the planetary gear set 230. The numericalvalue of the second forward speed ratio is determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 220, 230.

The third forward speed ratio is established with the engagement of theinput clutch 263, the braking synchronizer 268 and the synchronizer 270.The input clutch 263 connects the sun gear member 242 to the input shaft17. The braking synchronizer 268 connects the planet carrier assemblymember 256 to the transmission housing 280. The synchronizer 270connects the ring gear member 244 to the planet carrier assembly member256. The sun gear member 242 rotates at the same speed as the inputshaft 17. The planet carrier assembly member 246 and the ring gearmember 254 rotate at the same speed as the output shaft 19. The ringgear member 244 and the planet carrier assembly member 256 do notrotate. The planet carrier assembly member 246, and therefore the outputshaft 19, rotates at a speed determined from the speed of the sun gearmember 242 and the ring gear/sun gear tooth ratio of the planetary gearset 240. The numerical value of the third forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratio of the planetarygear set 240.

The fourth forward speed ratio is established with the engagement of theinput clutch 262, the braking synchronizer 265 and the synchronizer 266.The input clutch 262 connects the sun gear member 222 to the input shaft17. The braking synchronizer 265 connects the planet carrier assemblymember 226 to the transmission housing 280. The synchronizer 266connects the sun gear member 222 to the ring gear member 234. The sungear member 222 and the ring gear member 234 rotate at the same speed asthe input shaft 17. The planet carrier assembly member 226 does notrotate. The ring gear member 224 rotates at the same speed as the sungear member 232. The ring gear member 224 rotates at a speed determinedfrom the speed of the sun gear member 222 and the ring gear/sun geartooth ratio of the planetary gear set 220. The planet carrier assemblymember 236 and the planet carrier assembly member 246 rotate at the samespeed as the output shaft 19. The planet carrier assembly member 236,and therefore the output shaft 19, rotates at a speed determined fromthe speed of the ring gear member 234, the speed of the sun gear member232 and the ring gear/sun gear tooth ratio of the planetary gear set230. The numerical value of the fourth forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear set220, 230.

The fifth forward speed ratio is established with the engagement of theinput clutch 263, the braking synchronizer 269 and the synchronizer 270.The input clutch 263 connects the sun gear member 242 to the input shaft17. The braking synchronizer 269 connects the sun gear member 252 to thetransmission housing 280. The synchronizer 270 connects the ring gearmember 244 to the planet carrier assembly member 256. The sun gearmember 242 rotates at the same speed as the input shaft 17. The planetcarrier assembly member 246 and the ring gear member 254 rotate at thesame speed as the output shaft 19. The ring gear member 244 rotates atthe same speed as the planet carrier assembly member 256. The planetcarrier assembly member 246, and therefore the output shaft 19, rotatesat a speed determined from the speed of the ring gear member 244, thespeed of the sun gear member 242 and the ring gear/sun gear tooth ratioof the planetary gear set 240. The sun gear member 252 does not rotate.The ring gear member 254 rotates at a speed determined from the speed ofthe planet carrier assembly member 256 and the ring gear/sun gear toothratio of the planetary gear set 250. The numerical value of the fifthforward speed ratio is determined utilizing the ring gear/sun gear toothratios of the planetary gear sets 240, 250.

The sixth forward speed ratio is established with the engagement of theinput clutch 262, and the synchronizers 266, 267. In this configuration,the input shaft 17 is directly connected to the output shaft 19. Thenumerical value of the sixth forward speed ratio is 1.

As previously set forth, the truth table of FIG. 3b describes thecombinations of engagements utilized for six forward speed ratios andone reverse speed ratio. The truth table also provides an example ofspeed ratios that are available with the family member described above.These examples of speed ratios are determined the tooth ratios given inFIG. 3b. The R1/S1 value is the tooth ratio of the planetary gear set220; the R2/S2 value is the tooth ratio of the planetary gear set 230;the R3/S3 value is the tooth ratio of the planetary gear set 240; andthe R4/S4 value is the tooth ratio of the planetary gear set 250. Alsodepicted in FIG. 3b is a chart representing the ratio steps betweenadjacent forward speed ratios and the reverse speed ratio. For example,the first to second ratio interchange has a step of 1.83.

A powertrain 310, shown in FIG. 4a, includes the engine 12, a planetarytransmission 314, and the final drive mechanism 16. The planetarytransmission 314 includes an input shaft 17 continuously connected withthe engine 12, a planetary gear arrangement 318, and an output shaft 19continuously connected with the final drive mechanism 16. The planetarygear arrangement 318 includes four planetary gear sets 320, 330, 340 and350.

The planetary gear set 320 includes a sun gear member 322, a ring gearmember 324, and a planet carrier assembly member 326. The planet carrierassembly member 326 includes a plurality of pinion gears 327 rotatablymounted on a carrier member 329 and disposed in meshing relationshipwith both the sun gear member 322 and the ring gear member 324.

The planetary gear set 330 includes a sun gear member 332, a ring gearmember 334, and a planet carrier assembly member 336. The planet carrierassembly member 336 includes a plurality of intermeshing pinion gears337, 338 rotatably mounted on a carrier member 339 and disposed inmeshing relationship with the ring gear member 334 and the sun gearmember 332, respectively.

The planetary gear set 340 includes a sun gear member 342, a ring gearmember 344, and a planet carrier assembly member 346. The planet carrierassembly member 346 includes a plurality of pinion gears 347 rotatablymounted on a carrier member 349 and disposed in meshing relationshipwith both the sun gear member 342 and the ring gear member 344.

The planetary gear set 350 includes a sun gear member 352, a ring gearmember 354, and a planet carrier assembly member 356. The planet carrierassembly member 356 includes a plurality of pinion gears 357 rotatablymounted on a carrier member 359 and disposed in meshing relationshipwith both the sun gear member 352 and the ring gear member 354.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 320, 330, 340 and 350 are divided into first andsecond transmission subsets 360, 361 which are alternatively engaged toprovide odd number and even number speed ranges, respectively.Transmission subset 360 includes planetary gear sets 320 and 330, andtransmission subset 361 includes planetary gear sets 340 and 350. Theoutput shaft 19 is continuously connected with members of both subsets360 and 361.

As mentioned above, the first and second input clutches 362, 363 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 360 or transmission subset 361. The first and secondinput clutches 362, 363 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 360, 361 prior to engagingthe respective input clutches 362, 363. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms364, 365, 366, 367, 368, 369, 370 and 371. The torque transmittingmechanisms 364, 365, 368 and 369 comprise braking synchronizers, and thetorque transmitting mechanisms 366, 367, 370 and 371 comprise rotatingsynchronizers.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 360, 361 (i.e. through the clutch 362 tothe sun gear member 322 and through the clutch 363 to the sun gearmember 342). The ring gear member 324 is continuously connected with thesun gear member 332 through the interconnecting member 372. The ringgear member 334 is continuously connected with the planet carrierassembly member 346, the ring gear member 354 and the output shaft 19through the interconnecting member 374.

The sun gear member 322 is selectively connectable with the input shaft17 through the input clutch 362. The sun gear member 342 is selectivelyconnectable with the input shaft 17 through the input clutch 363. Theplanet carrier assembly member 326 is selectively connectable with thetransmission housing 380 through the braking synchronizer 364. Theplanet carrier assembly member 336 is selectively connectable with thetransmission housing 380 through the braking synchronizer 365. The sungear member 322 is selectively connectable with the planet carrierassembly member 336 through the synchronizer 366. The planet carrierassembly member 326 is selectively connectable with the sun gear member322 through the synchronizer 367. The planet carrier assembly member 356is selectively connectable with the transmission housing 380 through thebraking synchronizer 368. The sun gear member 352 is selectivelyconnectable with the transmission housing 380 through the brakingsynchronizer 369. The ring gear member 344 is selectively connectablewith the planet carrier assembly member 356 through the synchronizer370. The ring gear member 344 is selectively connectable with the sungear member 352 through the synchronizer 371.

The truth tables given in FIGS. 4b, 5b, 6 b, 7 b, 8 b, 9 b, 10 b, 11 b,12 b, 13 b and 14 b show the engagement sequences for the torquetransmitting mechanisms to provide at least five forward speed ratiosand one reverse speed ratio. As shown and described above for theconfigurations in FIGS. 1a, 2 a and 3 a, those skilled in the art willunderstand from the respective truth tables how the speed ratios areestablished through the planetary gear sets identified in the writtendescription.

The truth table shown in FIG. 4b describes the engagement combinationand engagement sequence necessary to provide the reverse drive ratio andsix forward speed ratios. A sample of the numerical values for theratios is also provided in the truth table of FIG. 4b. These values aredetermined utilizing the ring gear/sun gear tooth ratios also given inFIG. 4b. The R1/S1 value is the tooth ratio for the planetary gear set320; the R2/S2 value is the tooth ratio for the planetary gear set 330;the R3/S3 value is the tooth ratio for the planetary gear set 340; andthe R4/S4 value is the tooth ratio for the planetary gear set 350. Alsogiven in FIG. 4b is a chart describing the step ratios between theadjacent forward speed ratios and the reverse to first forward speedratio. For example, the first to second forward speed ratio step is1.68.

Those skilled in the art will recognize that the numerical values of thereverse and second forward speed ratios are determined utilizing thering gear/sun gear tooth ratios of the planetary gear sets 320, Thenumerical values of the first and fifth forward speed ratios aredetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 340, 350. The numerical value of the third forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratioof the planetary gear set 340. The numerical value of the fourth forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratioof the planetary gear set 330. The numerical value of the sixth forwardspeed ratio is 1.

A powertrain 410 shown in FIG. 5a includes a conventional engine 12, aplanetary transmission 414, and a conventional final drive mechanism 16.The planetary transmission 414 includes an input shaft 17 connected withthe engine 12, a planetary gear arrangement 418, and an output shaft 19continuously connected with the final drive mechanism 16. The planetarygear arrangement 418 includes four planetary gear sets 420, 430, 440 and450.

The planetary gear set 420 includes a sun gear member 422, a ring gearmember 424, and a planet carrier assembly member 426. The planet carrierassembly member 426 includes a plurality of pinion gears 427 rotatablymounted on a carrier member 429 and disposed in meshing relationshipwith both the sun gear member 422 and the ring gear member 424.

The planetary gear set 430 includes a sun gear member 432, a ring gearmember 434, and a planet carrier assembly member 436. The planet carrierassembly member 436 includes a plurality of pinion gears 437 rotatablymounted on a carrier member 439 and disposed in meshing relationshipwith both the sun gear member 432 and the ring gear member 434.

The planetary gear set 440 includes a sun gear member 442, a ring gearmember 444, and a planet carrier assembly member 446. The planet carrierassembly member 446 includes a plurality of pinion gears 447 rotatablymounted on a carrier member 449 and disposed in meshing relationshipwith both the sun gear member 442 and the ring gear member 444.

The planetary gear set 450 includes a sun gear member 452, a ring gearmember 454, and a planet carrier assembly member 456. The planet carrierassembly member 456 includes a plurality of intermeshing pinion gears457, 458 rotatably mounted on a carrier member 459 and disposed inmeshing relationship with the ring gear member 454 and the sun gearmember 452, respectively.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 420, 430, 440 and 450 are divided into first andsecond transmission subsets 460, 461 which are alternatively engaged toprovide odd number and even number speed ranges, respectively.Transmission subset 460 includes planetary gear sets 420 and 430, andtransmission subset 461 includes planetary gear sets 440 and 450. Theoutput shaft 19 is continuously connected with members of both subsets460 and 461.

As mentioned above, the first and second input clutches 462, 463 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 460 or transmission subset 461. The first and secondinput clutches 462, 463 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 460, 461 prior to engagingthe respective input clutches 462, 463. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms464, 465, 466, 467, 468, 469, 470 and 471. The torque transmittingmechanisms 464, 465, 468 and 469 comprise braking synchronizers, and thetorque transmitting mechanisms 466, 467, 470 and 471 comprise rotatingsynchronizers.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 460, 461 (i.e. through the clutch 462 tothe sun gear member 422 and through the clutch 463 to the sun gearmember 442). The ring gear member 424 is continuously connected with thesun gear member 432 through the interconnecting member 472. The ringgear member 434 is continuously connected with the planet carrierassembly member 446, the ring gear member 454 and the output shaft 19through the interconnecting member 474.

The sun gear member 422 is selectively connectable with the input shaft17 through the input clutch 462. The sun gear member 442 is selectivelyconnectable with the input shaft 17 through the input clutch 463. Theplanet carrier assembly member 426 is selectively connectable with thetransmission housing 480 through the braking synchronizer 464. Theplanet carrier assembly member 436 is selectively connectable with thetransmission housing 480 through the braking synchronizer 465. The sungear member 422 is selectively connectable with the planet carrierassembly member 436 through the synchronizer 466. The planet carrierassembly member 426 is selectively connectable with the sun gear member422 through the synchronizer 467. The planet carrier assembly member 456is selectively connectable with the transmission housing 480 through thebraking synchronizer 468. The sun gear member 452 is selectivelyconnectable with the transmission housing 480 through the brakingsynchronizer 469. The ring gear member 444 is selectively connectablewith the planet carrier assembly member 456 through the synchronizer470. The ring gear member 444 is selectively connectable with the sungear member 452 through the synchronizer 471.

As shown in FIG. 5b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio.

FIG. 5b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first ratio. For example, theratio step between the first and second forward ratios is 1.92. Thoseskilled in the art will recognize that the numerical value of thereverse speed ratio is determined utilizing the ring gear/sun gear toothratio of the planetary gear set 430. The numerical values of the firstand fifth forward speed ratios are determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 420, 430. Thenumerical value of the second forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set440. The numerical value of the third forward speed ratio is 1. Thenumerical values of the fourth and sixth forward speed ratios aredetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 440, 450.

A powertrain 510, shown in FIG. 6a, includes a conventional engine 12, apowertrain 514, and a conventional final drive mechanism 16. Thepowertrain 514 includes an input shaft 17 connected with the engine 12,a planetary gear arrangement 518, and an output shaft 19 continuouslyconnected with the final drive mechanism 16. The planetary geararrangement 518 includes four planetary gear sets 520, 530, 540 and 550.

The planetary gear set 520 includes a sun gear member 522, a ring gearmember 524, and a planet carrier assembly member 526. The planet carrierassembly member 526 includes a plurality of pinion gears 527 rotatablymounted on a carrier member 529 and disposed in meshing relationshipwith both the sun gear member 522 and the ring gear member 524.

The planetary gear set 530 includes a sun gear member 532, a ring gearmember 534, and a planet carrier assembly member 536. The planet carrierassembly member 536 includes a plurality of intermeshing pinion gears537, 538 rotatably mounted on a carrier member 539 and disposed inmeshing relationship with the ring gear member 534 and the sun gearmember 532, respectively.

The planetary gear set 540 includes a sun gear member 542, a ring gearmember 544, and a planet carrier assembly member 546. The planet carrierassembly member 546 includes a plurality of pinion gears 547 rotatablymounted on a carrier member 549 and disposed in meshing relationshipwith both the sun gear member 542 and the ring gear member 544.

The planetary gear set 550 includes a sun gear member 552, a ring gearmember 554, and a planet carrier assembly member 556. The planet carrierassembly member 556 includes a plurality of pinion gears 557 rotatablymounted on a carrier member 559 and disposed in meshing relationshipwith both the sun gear member 552 and the ring gear member 554.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 520, 530, 540 and 550 are divided into first andsecond transmission subsets 560, 561 which are alternatively engaged toprovide odd number and even number speed ranges, respectively.Transmission subset 560 includes planetary gear sets 520 and 530, andtransmission subset 561 includes planetary gear sets 540 and 550. Theoutput shaft 19 is continuously connected with members of both subsets560 and 561.

As mentioned above, the first and second input clutches 562, 563 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 560 or transmission subset 561. The first and secondinput clutches 562, 563 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 560, 561 prior to engagingthe respective input clutches 562, 563. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms564, 565, 566, 567, 568, 569, 570 and 571. The torque transmittingmechanisms 564, 565, 568 and 569 comprise braking synchronizers, and thetorque transmitting mechanisms 566, 567, 570 and 571 comprise rotatingsynchronizers.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 560, 561 (i.e. through the clutch 562 tothe sun gear member 522 and through the clutch 563 to the sun gearmember 542). The ring gear member 524 is continuously connected with thesun gear member 532 through the interconnecting member 572. The ringgear member 534 is continuously connected with the planet carrierassembly member 546, the ring gear member 554 and the output shaft 19through the interconnecting member 574.

The sun gear member 522 is selectively connectable with the input shaft17 through the input clutch 562. The sun gear member 542 is selectivelyconnectable with the input shaft 17 through the input clutch 563. Thering gear member 524 is selectively connectable with the transmissionhousing 580 through the braking synchronizer 564. The planet carrierassembly member 536 is selectively connectable with the transmissionhousing 580 through the braking synchronizer 565. The planet carrierassembly member 526 is selectively connectable with the planet carrierassembly member 536 through the synchronizer 566. The sun gear member522 is selectively connectable with the planet carrier assembly member536 through the synchronizer 567. The planet carrier assembly member 556is selectively connectable with the transmission housing 580 through thebraking synchronizer 568. The sun gear member 552 is selectivelyconnectable with the transmission housing 580 through the brakingsynchronizer 569. The ring gear member 544 is selectively connectablewith the planet carrier assembly member 556 through the synchronizer570. The ring gear member 544 is selectively connectable with the sungear member 552 through the synchronizer 571.

As shown in FIG. 6b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio. The chart of FIG. 6b describesthe ratio steps between adjacent forward speed ratios and the ratio stepbetween the reverse and first forward speed ratio.

Those skilled in the art, upon reviewing the truth table and theschematic representation of FIG. 6a can determine that the numericalvalues of the reverse and second forward speed ratios are determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets520, 530. The numerical values of the first and fifth forward speedratios are determined utilizing the ring gear/sun gear tooth ratios ofthe planetary gear sets 540, 550. The numerical value of the thirdforward speed ratio is determined utilizing the ring gear/sun gear toothratio of the planetary gear set 540. The numerical value of the fourthforward speed ratio is determined utilizing the ring gear/sun gear toothratio of the planetary gear set 530. The numerical value of the sixthforward speed ratio is 1.

The sample speed ratios given in the truth table are determinedutilizing the tooth ratio values also given in FIG. 6b. R1/S1 value isthe tooth ratio of the planetary gear set 520; the R2/S2 value is thetooth ratio of the planetary gear set 530; the R3/S3 value is the toothratio of the planetary gear set 540; and the R4/S4 value is the toothratio of the planetary gear set 550.

A powertrain 610, shown in FIG. 7a, has the engine and torque converter12, a planetary transmission 614, and the final drive mechanism 16. Theplanetary transmission 614 includes the input shaft 17, a planetary geararrangement 618, and the output shaft 19. The planetary gear arrangement618 includes four planetary gear sets 620, 630, 640 and 650.

The planetary gear set 620 includes a sun gear member 622, a ring gearmember 624, and a planet carrier assembly member 626. The planet carrierassembly member 626 includes a plurality of intermeshing pinion gears627, 628 rotatably mounted on a carrier member 629 and disposed inmeshing relationship with the ring gear member 624 and the sun gearmember 622, respectively.

The planetary gear set 630 includes a sun gear member 632, a ring gearmember 634, and a planet carrier assembly member 636. The planet carrierassembly member 636 includes a plurality of pinion gears 637 rotatablymounted on a carrier member 639 and disposed in meshing relationshipwith both the sun gear member 632 and the ring gear member 634.

The planetary gear set 640 includes a sun gear member 642, a ring gearmember 644, and a planet carrier assembly member 646. The planet carrierassembly member 646 includes a plurality of pinion gears 647 rotatablymounted on a carrier member 649 and disposed in meshing relationshipwith both the sun gear member 642 and the ring gear member 644.

The planetary gear set 650 includes a sun gear member 652, a ring gearmember 654, and a planet carrier assembly member 656. The planet carrierassembly member 656 includes a plurality of pinion gears 657 rotatablymounted on a carrier member 659 and disposed in meshing relationshipwith both the sun gear member 652 and the ring gear member 654.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 620, 630, 640 and 650 are divided into first andsecond transmission subsets 660, 661 which are alternatively engaged toprovide odd number and even number speed ranges, respectively.Transmission subset 660 includes planetary gear sets 620 and 630, andtransmission subset 661 includes planetary gear sets 640 and 650. Theoutput shaft 19 is continuously connected with members of both subsets660 and 661.

As mentioned above, the first and second input clutches 662, 663 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 660 or transmission subset 661. The first and secondinput clutches 662, 663 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 660, 661 prior to engagingthe respective input clutches 662, 663. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms664, 665, 666, 667, 668, 669, 670 and 671. The torque transmittingmechanisms 664, 665, 668 and 669 comprise braking synchronizers, and thetorque transmitting mechanisms 666, 667, 670 and 671 comprise rotatingsynchronizers.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 660, 661 (i.e. through the clutch 662 tothe sun gear member 632 and through the clutch 663 to the sun gearmember 642). The sun gear member 622 is continuously connected with theplanet carrier assembly member 636 through the interconnecting member672. The ring gear member 624 is continuously connected with the planetcarrier assembly member 646, the ring gear member 654 and the outputshaft 19 through the interconnecting member 674.

The sun gear member 632 is selectively connectable with the input shaft17 through the input clutch 662. The sun gear member 642 is selectivelyconnectable with the input shaft 17 through the input clutch 663. Thesun gear member 622 is selectively connectable with the transmissionhousing 680 through the braking synchronizer 664. The planet carrierassembly member 626 is selectively connectable with the transmissionhousing 680 through the braking synchronizer 665. The planet carrierassembly member 626 is selectively connectable with the ring gear member634 through the synchronizer 666. The ring gear member 634 isselectively connectable with the sun gear member 632 through thesynchronizer 667. The planet carrier assembly member 656 is selectivelyconnectable with the transmission housing 680 through the brakingsynchronizer 668. The sun gear member 652 is selectively connectablewith the transmission housing 680 through the braking synchronizer 669.The ring gear member 644 is selectively connectable with the planetcarrier assembly member 656 through the synchronizer 670. The ring gearmember 644 is selectively connectable with the sun gear member 652through the synchronizer 671.

As shown in FIG. 7b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio. The ratio values given are byway example and are established utilizing the ring gear/sun gear toothratios given in FIG. 7b. For example, the R1/S2 value is the tooth ratioof the planetary gear set 620; the R2/S2 value is the tooth ratio of theplanetary gear set 630; the R3/S3 value is the tooth ratio of theplanetary gear set 640; and the R4/S4 value is the tooth ratio of theplanetary gear set 650. The ratio steps between adjacent forward ratiosand the reverse to first ratio are also given in FIG. 7b.

Those skilled in the art will, upon reviewing the truth table of FIG.7b, recognize that the numerical values of the reverse and secondforward speed ratios are determined utilizing the ring gear/sun geartooth ratios of the planetary gear sets 620, 630. The numerical valuesof the first and fifth forward speed ratios are determined utilizing thering gear/sun gear tooth ratios of the planetary gear sets 640, 650. Thenumerical value of the third forward speed ratio is determined utilizingthe ring gear/sun gear tooth ratio of the planetary gear set 640. Thenumerical value of the fourth forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set620. The numerical value of the sixth forward speed ratio is 1.

A powertrain 710, shown in FIG. 8a, has the conventional engine 12, aplanetary transmission 714, and the conventional final drive mechanism16. The engine 12 is continuously connected with the input shaft 17. Theplanetary transmission 714 is drivingly connected with the final drivemechanism 16 through the output shaft 19. The planetary transmission 714includes a planetary gear arrangement 718 that has a first planetarygear set 720, a second planetary gear set 730, a third planetary gearset 740, and a fourth planetary gear set 750.

The planetary gear set 720 includes a sun gear member 722, a ring gearmember 724, and a planet carrier assembly member 726. The planet carrierassembly member 726 includes a plurality of intermeshing pinion gears727, 728 rotatably mounted on a carrier member 729 and disposed inmeshing relationship with the ring gear member 724 and the sun gearmember 722, respectively.

The planetary gear set 730 includes a sun gear member 732, a ring gearmember 734, and a planet carrier assembly member 736. The planet carrierassembly member 736 includes a plurality of pinion gears 737 rotatablymounted on a carrier member 739 and disposed in meshing relationshipwith both the sun gear member 732 and the ring gear member 734.

The planetary gear set 740 includes a sun gear member 742, a ring gearmember 744, and a planet carrier assembly member 746. The planet carrierassembly member 746 includes a plurality of pinion gears 747 rotatablymounted on a carrier member 749 and disposed in meshing relationshipwith both the sun gear member 742 and the ring gear member 744.

The planetary gear set 750 includes a sun gear member 752, a ring gearmember 754, and a planet carrier assembly member 756. The planet carrierassembly member 756 includes a plurality of intermeshing pinion gears757, 758 rotatably mounted on a carrier member 759 and disposed inmeshing relationship with the ring gear member 754 and the sun gearmember 752, respectively.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 720, 730, 740 and 750 are divided into first andsecond transmission subsets 760, 761 which are alternatively engaged toprovide odd number and even number speed ranges, respectively.Transmission subset 760 includes planetary gear sets 720 and 730, andtransmission subset 761 includes planetary gear sets 740 and 750. Theoutput shaft 19 is continuously connected with members of both subsets760 and 761.

As mentioned above, the first and second input clutches 762, 763 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 760 or transmission subset 761. The first and secondinput clutches 762, 763 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 760, 761 prior to engagingthe respective input clutches 762, 763. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms764, 765, 766, 767, 768, 769, 770 and 771. The torque transmittingmechanisms 764, 765, 768 and 769 comprise braking synchronizers, and thetorque transmitting mechanisms 766, 767, 770 and 771 comprise rotatingsynchronizers.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 760, 761 (i.e. through the clutch 762 tothe sun gear member 722 and through the clutch 763 to the sun gearmember 742). The planet carrier assembly member 726 is continuouslyconnected with the sun gear member 732 through the interconnectingmember 772. The ring gear member 734 is continuously connected with theplanet carrier assembly member 746, the ring gear member 754 and theoutput shaft 19 through the interconnecting member 774.

The sun gear member 722 is selectively connectable with the input shaft17 through the input clutch 762. The sun gear member 742 is selectivelyconnectable with the input shaft 17 through the input clutch 763. Thering gear member 724 is selectively connectable with the transmissionhousing 780 through the braking synchronizer 764. The planet carrierassembly member 736 is selectively connectable with the transmissionhousing 780 through the braking synchronizer 765. The sun gear member722 is selectively connectable with the planet carrier assembly member736 through the synchronizer 766. The planet carrier assembly member 726is selectively connectable with the sun gear member 722 through thesynchronizer 767. The planet carrier assembly member 756 is selectivelyconnectable with the transmission housing 780 through the brakingsynchronizer 768. The sun gear member 752 is selectively connectablewith the transmission housing 780 through the braking synchronizer 769.The ring gear member 744 is selectively connectable with the planetcarrier assembly member 756 through the synchronizer 770. The ring gearmember 744 is selectively connectable with the sun gear member 752through the synchronizer 771.

As shown in FIG. 8b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio. Also given in the truth table isa set of numerical values that are attainable with the present inventionutilizing the ring gear/sun gear tooth ratios given in FIG. 8b. TheR1/S1 value is the tooth ratio of the planetary gear set 720; the R2/S2value is the tooth ratio of the planetary gear set 730; the R3/S3 valueis the tooth ratio of the planetary gear set 740; and the R4/S4 value isthe tooth ratio of the planetary gear set 750.

FIG. 8b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first forward ratio. Forexample, the ratio step between the first and second forward ratios is1.78.

Those skilled in the art will recognize that the numerical value of thereverse speed ratio is determined utilizing the ring gear/sun gear toothratio of the planetary gear set 730. The numerical values of the firstand fifth forward speed ratios are determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 720, 730. Thenumerical value of the second forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set740. The numerical value of the third forward speed ratio is 1. Thenumerical values of the fourth and sixth forward speed ratios aredetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 740, 750.

A powertrain 810, shown in FIG. 9a, has the conventional engine 12, aplanetary transmission 814, and the final drive mechanism 16. The engine12 is continuously connected with the input shaft 17. The planetarytransmission 814 is drivingly connected with final drive mechanism 16through output shaft 19. The planetary transmission 814 includes aplanetary gear arrangement 818 that has a first planetary gear set 820,a second planetary gear set 830, a third planetary gear set 840, andfourth planetary gear set 850.

The planetary gear set 820 includes a sun gear member 822, a ring gearmember 824, and a planet carrier assembly member 826. The planet carrierassembly member 826 includes a plurality of intermeshing pinion gears827, 828 rotatably mounted on a carrier member 829 and disposed inmeshing relationship with the ring gear member 824 and the sun gearmember 822, respectively.

The planetary gear set 830 includes a sun gear member 832, a ring gearmember 834, and a planet carrier assembly member 836. The planet carrierassembly member 836 includes a plurality of intermeshing pinion gears837, 838 rotatably mounted on a carrier member 839 and disposed inmeshing relationship with the ring gear member 834 and the sun gearmember 832, respectively.

The planetary gear set 840 includes a sun gear member 842, a ring gearmember 844, and a planet carrier assembly member 846. The planet carrierassembly member 846 includes a plurality of pinion gears 847 rotatablymounted on a carrier member 849 and disposed in meshing relationshipwith both the sun gear member 842 and the ring gear member 844.

The planetary gear set 850 includes a sun gear member 852, a ring gearmember 854, and a planet carrier assembly member 856. The planet carrierassembly member 856 includes a plurality of pinion gears 857 rotatablymounted on a carrier member 859 and disposed in meshing relationshipwith both the sun gear member 852 and the ring gear member 854.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 820, 830, 840 and 850 are divided into first andsecond transmission subsets 860, 861 which are alternatively engaged toprovide odd number and even number speed ranges, respectively.Transmission subset 860 includes planetary gear sets 820 and 830, andtransmission subset 861 includes planetary gear sets 840 and 850. Theoutput shaft 19 is continuously connected with members of both subsets860 and 861.

As mentioned above, the first and second input clutches 862, 863 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 860 or transmission subset 861. The first and secondinput clutches 862, 863 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratioselection is preselected within the transmission subsets 860, 861 priorto engaging the respective input clutches 862, 863. The preselection isachieved by means of electronically controlled synchronizers. As shown,the planetary gear arrangement includes eight torque transmittingmechanisms 864, 865, 866, 867, 868, 869, 870 and 871. The torquetransmitting mechanisms 864, 865, 868 and 869 comprise brakingsynchronizers, and the torque transmitting mechanisms 866, 867, 870 and871 comprise rotating synchronizers.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 860, 861 (i.e. through the clutch 862 tothe sun gear member 822 and through the clutch 863 to the sun gearmember 842). The planet carrier assembly member 826 is continuouslyconnected with the sun gear member 832 through the interconnectingmember 872. The ring gear member 834 is continuously connected with theplanet carrier assembly member 846, the ring gear member 854 and theoutput shaft 19 through the interconnecting member 874.

The sun gear member 822 is selectively connectable with the input shaft17 through the input clutch 862. The sun gear member 842 is selectivelyconnectable with the input shaft 17 through the input clutch 863. Theplanet carrier assembly member 826 is selectively connectable with thetransmission housing 880 through the braking synchronizer 864. Theplanet carrier assembly member 836 is selectively connectable with thetransmission housing 880 through the braking synchronizer 865. The ringgear member 824 is selectively connectable with the planet carrierassembly member 836 through the synchronizer 866. The sun gear member822 is selectively connectable with the planet carrier assembly member836 through the synchronizer 867. The planet carrier assembly member 856is selectively connectable with the transmission housing 880 through thebraking synchronizer 868. The sun gear member 852 is selectivelyconnectable with the transmission housing 880 through the brakingsynchronizer 869. The ring gear member 844 is selectively connectablewith the planet carrier assembly member 856 through the synchronizer870. The ring gear member 844 is selectively connectable with the sungear member 852 through the synchronizer 871.

As shown in FIG. 9b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio. A sample of numerical values forthe individual ratios is also given in the truth table of FIG. 9b. Thesenumerical values have been calculated using the ring gear/sun gear toothratios also given by way of example in FIG. 9b. The R1/S1 value is thetooth ratio of the planetary gear set 820; the R2/S2 value is the toothratio of planetary gear set 830; the R3/S3 value is the tooth ratio ofthe planetary gear set 840; and the R4/S4 value is the tooth ratio ofthe planetary gear set 850. FIG. 9b also describes the ratio stepsbetween adjacent forward ratios and between the reverse and firstforward ratio. For example, the ratio step between the first and secondforward ratios is 1.60.

Those skilled in the art of planetary transmissions will recognize thatthe numerical values of the reverse and second forward speed ratios aredetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 820, 830. The numerical values of the first andfifth forward speed ratios are determined utilizing the ring gear/sungear tooth ratios of the planetary gear sets 840, 850. The numericalvalue of the third forward speed ratio is determined utilizing the ringgear/sun gear tooth ratio of the planetary gear set 840. The numericalvalue of the fourth forward speed ratio is determined utilizing the ringgear/sun gear tooth ratio of the planetary gear set 830. The numericalvalue of the sixth forward speed ratio is 1.

Referring to FIG. 10a, a powertrain 910 is shown having a conventionalengine 12, a planetary transmission 914, and a conventional final drivemechanism 16. The planetary transmission 914 includes an input shaft 17connected with the engine 12, a planetary gear arrangement 918, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 918 includes four planetary gear sets920, 930, 940 and 950.

The planetary gear set 920 includes a sun gear member 922, a ring gearmember 924, and a planet carrier assembly member 926. The planet carrierassembly member 926 includes a plurality of pinion gears 927 rotatablymounted on a carrier member 929 and disposed in meshing relationshipwith both the sun gear member 922 and the ring gear member 924.

The planetary gear set 930 includes a sun gear member 932, a ring gearmember 934, and a planet carrier assembly member 936. The planet carrierassembly member 936 includes a plurality of intermeshing pinion gears937, 938 rotatably mounted on a carrier member 939 and disposed inmeshing relationship with the ring gear member 934 and the sun gearmember 932, respectively.

The planetary gear set 940 includes a sun gear member 942, a ring gearmember 944, and a planet carrier assembly member 946. The planet carrierassembly member 946 includes a plurality of pinion gears 947 rotatablymounted on a carrier member 949 and disposed in meshing relationshipwith both the sun gear member 942 and the ring gear member 944.

The planetary gear set 950 includes a sun gear member 952, a ring gearmember 954, and a planet carrier assembly member 956. The planet carrierassembly member 956 includes a plurality of pinion gears 957 rotatablymounted on a carrier member 959 and disposed in meshing relationshipwith both the sun gear member 952 and the ring gear member 954.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 920, 930, 940 and 950 are divided into first andsecond transmission subsets 960, 961 which are alternatively engaged toprovide odd number and even number speed ranges, respectively.Transmission subset 960 includes planetary gear sets 920 and 930, andtransmission subset 961 includes planetary gear sets 940 and 950. Theoutput shaft 19 is continuously connected with members of both subsets960 and 961.

As mentioned above, the first and second input clutches 962, 963 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 960 or transmission subset 961. The first and secondinput clutches 962, 963 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 960, 961 prior to engagingthe respective input clutches 962, 963. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms964, 965, 966, 967, 968, 969, 970 and 971. The torque transmittingmechanisms 964, 965, 968 and 969 comprise braking synchronizers, and thetorque transmitting mechanisms 966, 967, 970 and 971 comprise rotatingsynchronizers.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 960, 961 (i.e. through the clutch 962 tothe sun gear member 922 and through the clutch 963 to the sun gearmember 942). The ring gear member 924 is continuously connected with thesun gear member 932 through the interconnecting member 972. The ringgear member 934 is continuously connected with the planet carrierassembly member 946, the ring gear member 954 and the output shaft 19through the interconnecting member 974.

The sun gear member 922 is selectively connectable with the input shaft17 through the input clutch 962. The sun gear member 942 is selectivelyconnectable with the input shaft 17 through the input clutch 963. Thering gear member 924 is selectively connectable with the transmissionhousing 980 through the braking synchronizer 964. The planet carrierassembly member 926 is selectively connectable with the transmissionhousing 980 through the braking synchronizer 965. The planet carrierassembly member 926 is selectively connectable with the planet carrierassembly member 936 through the synchronizer 966. The sun gear member922 is selectively connectable with the planet carrier assembly member936 through the synchronizer 967. The planet carrier assembly member 956is selectively connectable with the transmission housing 980 through thebraking synchronizer 968. The sun gear member 952 is selectivelyconnectable with the transmission housing 980 through the brakingsynchronizer 969. The ring gear member 944 is selectively connectablewith the planet carrier assembly member 956 through the synchronizer970. The ring gear member 944 is selectively connectable with the sungear member 952 through the synchronizer 971.

As shown in FIG. 10b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide seven forwardspeed ratios and a reverse speed ratio. The truth table also provides aset of examples for the numerical values for each of the reverse andforward speed ratios. These numerical values have been determinedutilizing the ring gear/sun gear tooth ratios given in FIG. 10b. TheR1/S1 value is the tooth ratio of the planetary gear set 920; the R2/S2value is the tooth ratio of the planetary gear set 930; the R3/S3 valueis the tooth ratio of the planetary gear set 940; and the R4/S4 value isthe tooth ratio of the planetary gear set 950.

Those skilled in the art, upon reviewing the engagement combinations,will recognize that the numerical values of the reverse, first and thirdforward speed ratios are determined utilizing the ring gear/sun geartooth ratios of the planetary gear sets 920, 930. The numerical valuesof the second and sixth forward speed ratios are determined utilizingthe ring gear/sun gear tooth ratios of the planetary gear sets 940, 950.The numerical value of the fourth forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set940. The numerical value of the fifth forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set930. The numerical value of the seventh forward speed ratio is 1.

Referring to FIG. 11a, a powertrain 1010 is shown having a conventionalengine 12, a planetary transmission 1014, and a conventional final drivemechanism 16. The planetary transmission 1014 includes an input shaft 17connected with the engine 12, a planetary gear arrangement 1018, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 1018 includes four planetary gearsets 1020, 1030, 1040 and 1050.

The planetary gear set 1020 includes a sun gear member 1022, a ring gearmember 1024, and a planet carrier assembly member 1026. The planetcarrier assembly member 1026 includes a plurality of pinion gears 1027rotatably mounted on a carrier member 1029 and disposed in meshingrelationship with both the sun gear member 1022 and the ring gear member1024.

The planetary gear set 1030 includes a sun gear member 1032, a ring gearmember 1034, and a planet carrier assembly member 1036. The planetcarrier assembly member 1036 includes a plurality of intermeshing piniongears 1037, 1038 rotatably mounted on a carrier member 1039 and disposedin meshing relationship with the ring gear member 1034 and the sun gearmember 1032, respectively.

The planetary gear set 1040 includes a sun gear member 1042, a ring gearmember 1044, and a planet carrier assembly member 1046. The planetcarrier assembly member 1046 includes a plurality of pinion gears 1047rotatably mounted on a carrier member 1049 and disposed in meshingrelationship with both the sun gear member 1042 and the ring gear member1044.

The planetary gear set 1050 includes a sun gear member 1052, a ring gearmember 1054, and a planet carrier assembly member 1056. The planetcarrier assembly member 1056 includes a plurality of intermeshing piniongears 1057, 1058 rotatably mounted on a carrier member 1059 and disposedin meshing relationship with the ring gear member 1054 and the sun gearmember 1052, respectively.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 1020, 1030, 1040 and 1050 are divided into first andsecond transmission subsets 1060, 1061 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 1060 includes planetary gear sets 1020 and 1030, andtransmission subset 1061 includes planetary gear sets 1040 and 1050. Theoutput shaft 19 is continuously connected with members of both subsets1060 and 1061.

As mentioned above, the first and second input clutches 1062, 1063 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 1060 or transmission subset 1061. The first andsecond input clutches 1062, 1063 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 1060, 1061 prior to engagingthe respective input clutches 1062, 1063. The preselection is achievedby means of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms1064, 1065, 1066, 1067, 1068, 1069, 1070 and 1071. The torquetransmitting mechanisms 1064, 1065, 1068 and 1069 comprise brakingsynchronizers, and the torque transmitting mechanisms 1066, 1067, 1070and 1071 comprise rotating synchronizers.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 1060, 1061 (i.e. through the clutch 1062to the sun gear member 1022 and through the clutch 1063 to the sun gearmember 1042). The ring gear member 1024 is continuously connected withthe sun gear member 1032 through the interconnecting member 1072. Theplanet carrier assembly member 1046 is continuously connected with thering gear member 1034, the sun gear member 1052 and the output shaft 19through the interconnecting member 1074.

The sun gear member 1022 is selectively connectable with the input shaft17 through the input clutch 1062. The sun gear member 1042 isselectively connectable with the input shaft 17 through the input clutch1063. The ring gear member 1024 is selectively connectable with thetransmission housing 1080 through the braking synchronizer 1064. Theplanet carrier assembly member 1026 is selectively connectable with thetransmission housing 1080 through the braking synchronizer 1065. Theplanet carrier assembly member 1026 is selectively connectable with theplanet carrier assembly member 1036 through the synchronizer 1066. Thesun gear member 1022 is selectively connectable with the planet carrierassembly member 1036 through the synchronizer 1067. The ring gear member1054 is selectively connectable with the transmission housing 1080through the braking synchronizer 1068. The planet carrier assemblymember 1056 is selectively connectable with the transmission housing1080 through the braking synchronizer 1069. The ring gear member 1044 isselectively connectable with the ring gear member 1054 through thesynchronizer 1070. The ring gear member 1044 is selectively connectablewith the planet carrier assembly member 1056 through the synchronizer1071.

As shown in FIG. 11b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide seven forwardspeed ratios and a reverse speed ratio. The truth table also provides aset of examples for the numerical values for each of the reverse andforward speed ratios. These numerical values have been determinedutilizing the ring gear/sun gear tooth ratios given in FIG. 11b. TheR1/S1 value is the tooth ratio of the planetary gear set 1020; the R2/S2value is the tooth ratio of the planetary gear set 1030; the R3/S3 valueis the tooth ratio of the planetary gear set 1040; and the R4/S4 valueis the tooth ratio of the planetary gear set 1050.

Those skilled in the art, upon reviewing the engagement combinations,will recognize that the numerical values of the reverse, first and thirdforward speed ratios are determined utilizing the ring gear/sun geartooth ratios of the planetary gear set 1020, 1030. The numerical valuesof the second and sixth forward speed ratios are determined utilizingthe ring gear/sun gear tooth ratios of the planetary gear set 1040,1050. The numerical value of the fourth forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratio of the planetarygear set 1040. The numerical value of the fifth forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratio of the planetarygear set 1030. The numerical value of the seventh forward speed ratio is1.

Referring to FIG. 12a, a powertrain 1110 is shown having a conventionalengine 12, a planetary transmission 1114, and a conventional final drivemechanism 16. The planetary transmission 1114 includes an input shaft 17connected with the engine 12, a planetary gear arrangement 1118, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 1118 includes four planetary gearsets 1120, 1130, 1140 and 1150.

The planetary gear set 1120 includes a sun gear member 1122, a ring gearmember 1124, and a planet carrier assembly member 1126. The planetcarrier assembly member 1126 includes a plurality of pinion gears 1127rotatably mounted on a carrier member 1129 and disposed in meshingrelationship with both the sun gear member 1122 and the ring gear member1124.

The planetary gear set 1130 includes a sun gear member 1132, a ring gearmember 1134, and a planet carrier assembly member 1136. The planetcarrier assembly member 1136 includes a plurality of intermeshing piniongears 1137, 1138 rotatably mounted on a carrier member 1139 and disposedin meshing relationship with the ring gear member 1134 and the sun gearmember 1132, respectively.

The planetary gear set 1140 includes a sun gear member 1142, a ring gearmember 1144, and a planet carrier assembly member 1146. The planetcarrier assembly member 1146 includes a plurality of pinion gears 1147rotatably mounted on a carrier member 1149 and disposed in meshingrelationship with both the sun gear member 1142 and the ring gear member1144.

The planetary gear set 1150 includes a sun gear member 1152, a ring gearmember 1154, and a planet carrier assembly member 1156. The planetcarrier assembly member 1156 includes a plurality of pinion gears 1157rotatably mounted on a carrier member 1159 and disposed in meshingrelationship with both the sun gear member 1152 and the ring gear member1154.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 1120, 1130, 1140 and 1150 are divided into first andsecond transmission subsets 1160, 1161 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 1160 includes planetary gear sets 1120 and 1130, andtransmission subset 1161 includes planetary gear sets 1140 and 1150. Theoutput shaft 19 is continuously connected with members of both subsets1160 and 1161.

As mentioned above, the first and second input clutches 1162, 1163 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 1160 or transmission subset 1061. The first andsecond input clutches 1162, 1163 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 1160, 1161 prior to engagingthe respective input clutches 1162, 1163. The preselection is achievedby means of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms1164, 1165, 1166, 1167, 1168, 1169, 1170 and 1171. The torquetransmitting mechanisms 1164, 1165, 1168 and 1169 comprise brakingsynchronizers, and the torque transmitting mechanisms 1166, 1167, 1170and 1171 comprise rotating synchronizers.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 1160, 1161 (i.e. through the clutch 1162to the sun gear member 1122 and through the clutch 1163 to the sun gearmember 1142). The planet carrier assembly member 1126 is continuouslyconnected with the sun gear member 1132 through the interconnectingmember 1172. The planet carrier assembly member 1146 is continuouslyconnected with the ring gear member 1134, the ring gear member 1154 andthe output shaft 19 through the interconnecting member 1174.

The sun gear member 1122 is selectively connectable with the input shaft17 through the input clutch 1162. The sun gear member 1142 isselectively connectable with the input shaft 17 through the input clutch1163. The planet carrier assembly member 1126 is selectively connectablewith the transmission housing 1180 through the braking synchronizer1164. The ring gear member 1124 is selectively connectable with thetransmission housing 1180 through the braking synchronizer 1165. The sungear member 1122 is selectively connectable with the planet carrierassembly member 1136 through the synchronizer 1166. The ring gear member1124 is selectively connectable with the planet carrier assembly member1136 through the synchronizer 1167. The planet carrier assembly member1156 is selectively connectable with the transmission housing 1180through the braking synchronizer 1168. The sun gear member 1152 isselectively connectable with the transmission housing 1180 through thebraking synchronizer 1169. The ring gear member 1144 is selectivelyconnectable with the planet carrier assembly member 1156 through thesynchronizer 1170. The ring gear member 1144 is selectively connectablewith the sun gear member 1152 through the synchronizer 1171.

As shown in FIG. 12b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide seven forwardspeed ratios and a reverse speed ratio. The truth table also provides aset of examples for the numerical values for each of the reverse andforward speed ratios. These numerical values have been determinedutilizing the ring gear/sun gear tooth ratios given in FIG. 12b. TheR1/S1 value is the tooth ratio of the planetary gear set 1120; the R2/S2value is the tooth ratio of the planetary gear set 1130; the R3/S3 valueis the tooth ratio of the planetary gear set 1140; and the R4/S4 valueis the tooth ratio of the planetary gear set 1150.

Those skilled in the art, upon reviewing the engagement combinations,will recognize that the numerical values of the reverse, second andsixth forward speed ratios are determined utilizing the ring gear/sungear tooth ratios of the planetary gear sets 1120, 1130. The numericalvalues of the first and fifth forward speed ratios are determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets1140, 1150. The numerical value of the third forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratio of the planetarygear set 1140. The numerical value of the fourth forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratio of the planetarygear set 1130. The numerical value of the seventh forward speed ratio is1.

Referring to FIG. 13a, a powertrain 1210 is shown having a conventionalengine 12, a planetary transmission 1214, and a conventional final drivemechanism 16. The planetary transmission 1214 includes an input shaft 17connected with the engine 12, a planetary gear arrangement 1218, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 1218 includes four planetary gearsets 1220, 1230, 1240 and 1250.

The planetary gear set 1220 includes a sun gear member 1222, a ring gearmember 1224, and a planet carrier assembly member 1226. The planetcarrier assembly member 1226 includes a plurality of pinion gears 1227rotatably mounted on a carrier member 1229 and disposed in meshingrelationship with both the sun gear member 1222 and the ring gear member1224.

The planetary gear set 1230 includes a sun gear member 1232, a ring gearmember 1234, and a planet carrier assembly member 1236. The planetcarrier assembly member 1236 includes a plurality of intermeshing piniongears 1237, 1238 rotatably mounted on a carrier member 1239 and disposedin meshing relationship with the ring gear member 1234 and the sun gearmember 1232, respectively.

The planetary gear set 1240 includes a sun gear member 1242, a ring gearmember 1244, and a planet carrier assembly member 1246. The planetcarrier assembly member 1246 includes a plurality of pinion gears 1247rotatably mounted on a carrier member 1249 and disposed in meshingrelationship with both the sun gear member 1242 and the ring gear member1244.

The planetary gear set 1250 includes a sun gear member 1252, a ring gearmember 1254, and a planet carrier assembly member 1256. The planetcarrier assembly member 1256 includes a plurality of intermeshing piniongears 1257, 1258 rotatably mounted on a carrier member 1259 and disposedin meshing relationship with the ring gear member 1254 and the sun gearmember 1252, respectively.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 1220, 1230, 1240 and 1250 are divided into first andsecond transmission subsets 1260, 1261 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 1260 includes planetary gear sets 1220 and 1230, andtransmission subset 1261 includes planetary gear sets 1240 and 1250. Theoutput shaft 19 is continuously connected with members of both subsets1260 and 1261.

As mentioned above, the first and second input clutches 1262, 1263 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 1260 or transmission subset 1261. The first andsecond input clutches 1262, 1263 are controlled electronically and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 1260, 1261 prior to engagingthe respective input clutches 1262, 1263. The preselection is achievedby means of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms1264, 1265, 1266, 1267, 1268, 1269, 1270 and 1271. The torquetransmitting mechanisms 1264, 1265, 1268 and 1269 comprise brakingsynchronizers, and the torque transmitting mechanisms 1266, 1267, 1270and 1271 comprise rotating synchronizers.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 1260, 1261 (i.e. through the clutch 1262to the sun gear member 1222 and through the clutch 1263 to the sun gearmember 1242). The planet carrier assembly member 1226 is continuouslyconnected with the sun gear member 1232 through the interconnectingmember 1272. The planet carrier assembly member 1246 is continuouslyconnected with the ring gear member 1234, the sun gear member 1252, andthe output shaft 19 through the interconnecting member 1274.

The sun gear member 1222 is selectively connectable with the input shaft17 through the input clutch 1262. The sun gear member 1242 isselectively connectable with the input shaft 17 through the input clutch1263. The planet carrier assembly member 1226 is selectively connectablewith the transmission housing 1280 through the braking synchronizer1264. The ring gear member 1224 is selectively connectable with thetransmission housing 1280 through the braking synchronizer 1265. The sungear member 1222 is selectively connectable with the planet carrierassembly member 1236 through the synchronizer 1266. The ring gear member1224 is selectively connectable with the planet carrier assembly member1236 through the synchronizer 1267. The ring gear member 1254 isselectively connectable with the transmission housing 1280 through thebraking synchronizer 1268. The planet carrier assembly member 1256 isselectively connectable with the transmission housing 1280 through thebraking synchronizer 1269. The ring gear member 1244 is selectivelyconnectable with the ring gear member 1254 through the synchronizer1270. The ring gear member 1244 is selectively connectable with theplanet carrier assembly member 1256 through the synchronizer 1271.

As shown in FIG. 13b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide seven forwardspeed ratios and a reverse speed ratio. The truth table also provides aset of examples for the numerical values for each of the reverse andforward speed ratios. These numerical values have been determinedutilizing the ring gear/sun gear tooth ratios given in FIG. 13b. TheR1/S1 value is the tooth ratio of the planetary gear set 1220; the R2/S2value is the tooth ratio of the planetary gear set 1230; the R3/S3 valueis the tooth ratio of the planetary gear set 1240; and the R4/S4 valueis the tooth ratio of the planetary gear set 1250.

Those skilled in the art, upon reviewing the engagement combinations,will recognize that the numerical values of the reverse, second andsixth forward speed ratios are determined utilizing the ring gear/sungear tooth ratios of the planetary gear sets 1220, 1230. The numericalvalues of the first and fifth forward speed ratios are determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets1240, 1250. The numerical value of the third forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratio of the planetarygear set 1240. The numerical value of the fourth forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratio of the planetarygear set 1230. The numerical value of the seventh forward speed ratio is1.

FIGS. 14a and 14 b illustrate a transmission wherein one of the torquetransmitting mechanisms from a previously described configuration iseliminated to realize five forward speed ratios and a reverse speedratio. Specifically, the powertrain 1310, shown in FIG. 14a is identicalto that shown in FIG. 5a, except that the synchronizer 471 of FIG. 5ahas been eliminated.

The powertrain 1310, shown in FIG. 14a, includes the conventional engine12, a planetary transmission 1314, and the conventional final drivemechanism 16. The engine 12 is selectively connectable with theplanetary transmission 1314 through the input shaft 17. The planetarytransmission is drivingly connected with the final drive mechanism 16through the input shaft 17. The planetary transmission 1314 includes aplanetary gear arrangement 1318 that has a first planetary gear set1320, a second planetary gear set 1330, a third planetary gear set 1340,and a fourth planetary gear set 1350.

The planetary gear set 1320 includes a sun gear member 1322, a ring gearmember 1324, and a planet carrier assembly member 1326. The planetcarrier assembly member 1326 includes a plurality of pinion gears 1327rotatably mounted on a carrier member 1329 and disposed in meshingrelationship with both the sun gear member 1322 and the ring gear member1324.

The planetary gear set 1330 includes a sun gear member 1332, a ring gearmember 1334, and a planet carrier assembly member 1336. The planetcarrier assembly member 1336 includes a plurality of pinion gears 1337rotatably mounted on a carrier member 1339 and disposed in meshingrelationship with both the sun gear member 1332 and the ring gear member1334.

The planetary gear set 1340 includes a sun gear member 1342, a ring gearmember 1344, and a planet carrier assembly member 1346. The planetcarrier assembly member 1346 includes a plurality of pinion gears 1347rotatably mounted on a carrier member 1349 and disposed in meshingrelationship with both the sun gear member 1342 and the ring gear member1344.

The planetary gear set 1350 includes a sun gear member 1352, a ring gearmember 1354, and a planet carrier assembly member 1356. The planetcarrier assembly member 1356 includes a plurality of intermeshing piniongears 1357, 1358 rotatably mounted on a carrier member 1359 and disposedin meshing relationship with the ring gear member 1354 and the sun gearmember 1352, respectively.

As a result of the dual clutch arrangement of the invention, the fourplanetary gear sets 1320, 1330, 1340 and 1350 are divided into first andsecond transmission subsets 1360, 1361 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 1360 includes planetary gear sets 1320 and 1330, andtransmission subset 1361 includes planetary gear sets 1340 and 1350. Theoutput shaft 19 is continuously connected with members of both subsets1360 and 1361.

As mentioned above, the first and second input clutches 1362, 1363 arealternatively engaged for transmitting power from the input shaft 17 totransmission subset 1360 or transmission subset 1361. The first andsecond input clutches 1362, 1363 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 1360, 1361 prior to engagingthe respective input clutches 1362, 1363. The preselection is achievedby means of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes seven torque transmitting mechanisms1364, 1365, 1366, 1367, 1368, 1369 and 1370. The torque transmittingmechanism 1364, 1365, 1368 and 1369 comprise braking synchronizers, andthe torque transmitting mechanisms 1366, 1367 and 1370 comprise rotatingsynchronizers.

Accordingly, the input shaft 17 is alternately connected with the firstand second transmission subsets 1360, 1361 (i.e. through the clutch 1362to the sun gear member 1322 and through the clutch 1363 to the sun gearmember 1342). The ring gear member 1324 is continuously connected withthe sun gear member 1332 through the interconnecting member 1372. Theplanet carrier assembly member 1346 is continuously connected with thering gear members 1334, 1354 and the output shaft 19 through theinterconnecting member 1374.

The sun gear member 1322 is selectively connectable with the input shaft17 through the input clutch 1362. The sun gear member 1342 isselectively connectable with the input shaft 17 through the input clutch1363. The planet carrier assembly member 1326 is selectively connectablewith the transmission housing 1380 through the braking synchronizer1364. The planet carrier assembly member 1336 is selectively connectablewith the transmission housing 1380 through the braking synchronizer1365. The sun gear member 1322 is selectively connectable with theplanet carrier assembly member 1336 through the synchronizer 1366. Theplanet carrier assembly member 1326 is selectively connectable with thesun gear member 1322 through the synchronizer 1367. The planet carrierassembly member 1356 is selectively connectable with the transmissionhousing 1380 through the braking synchronizer 1368. The sun gear member1352 is selectively connectable with the transmission housing 1380through the braking synchronizer 1369. The ring gear member 1344 isselectively connectable with the planet carrier assembly member 1356through the synchronizer 1370.

As shown in FIG. 13b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide five forwardspeed ratios and a reverse speed ratio. A sample of the numerical valuesfor the ratios is also provided in the truth table of the FIG. 13b.These values are determined utilizing the ring gear/sun gear toothratios also given in FIG. 13 b. The R1/S1 value is the tooth ratio ofthe planetary gear set 1320; the R2/S2 value is the tooth ratio of theplanetary gear set 1330; the R3/S3 value is the tooth ratio of theplanetary gear set 1340; and the R4/S4 value is the tooth ratio of theplanetary gear set 1350. Also given in FIG. 13b is a chart describingthe step ratios between the adjacent forward speed ratios and thereverse to first forward speed ratio.

Those skilled in the art will recognize that the numerical value of thereverse speed ratio is determined utilizing the ring gear/sun gear toothratio of the planetary gear set 1330. The numerical values of the firstand fifth forward speed ratios are determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 1320, 1330. Thenumerical value of the second forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set1340. The numerical value of the third forward speed ratio is 1. Thenumerical value of the fourth forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets1340, 1350.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

What is claimed is:
 1. A multi-speed transmission comprising: an inputshaft; an output shaft; first, second, third and fourth planetary gearsets each having first, second and third members; a firstinterconnecting member continuously interconnecting said first member ofsaid first planetary gear set with said first member of said secondplanetary gear set; a second interconnecting member continuouslyinterconnecting said second member of said second planetary gear setwith said first member of said third planetary gear set, said firstmember of said fourth planetary gear set and said output shift; a firstinput clutch selectively interconnecting said input shaft with saidsecond member of said first planetary gear set; a second input clutchselectively interconnecting said input shaft with said second member ofsaid third planetary gear set; a first torque-transmitting mechanismselectively interconnecting said third member of said second planetarygear set with a member of said first planetary gear set; a secondtorque-transmitting mechanism selectively interconnecting said secondmember of said first planetary gear set with another member of saidfirst or second planetary gear set; a third torque-transmittingmechanism selectively interconnecting said third member of said thirdplanetary gear set with said second member of said fourth planetary gearset; a fourth torque-transmitting mechanism selectively interconnectingsaid third member of said third planetary gear set with said thirdmember of said fourth planetary gear set; a fifth torque-transmittingmechanism selectively interconnecting said first or third members ofsaid first planetary gear set with a stationary member; a sixthtorque-transmitting mechanism selectively interconnecting said thirdmember of said first or second planetary gear set with said stationarymember, said member interconnected with said stationary member by saidsixth torque-transmitting mechanism being different from said memberinterconnected with said stationary member by said fifthtorque-transmitting mechanism; a seventh torque-transmitting mechanismselectively interconnecting said second member of said fourth planetarygear set with said stationary member; an eighth torque-transmittingmechanism selectively interconnecting said third member of said fourthplanetary gear set with said stationary member; said input clutches andtorque-transmitting mechanisms being engaged in combinations of at leastthree to provide at least six forward speed ratios and a reverse speedratio.
 2. The transmission defined in claim 1, wherein said eighttorque-transmitting mechanisms comprise synchronizers.
 3. Thetransmission defined in claim 1, wherein said fifth, sixth, seventh andeighth torque-transmitting mechanisms comprise braking synchronizers,and said first, second, third and fourth torque-transmitting mechanismscomprise rotating synchronizers.
 4. The transmission defined in claim 1,wherein said first input clutch is applied for odd number speed rangesand said second input clutch is applied for even number speed ranges. 5.The transmission defined in claim 1, wherein said first input clutch isapplied for even number speed ranges and said second input clutch isapplied for odd number speed ranges.
 6. The transmission defined inclaim 1, wherein said first input clutch and said second input clutchare interchangeable to shift from odd number speed ranges to even numberspeed ranges, and vice versa.
 7. The transmission defined in claim 1,wherein selected ones of said eight torque-transmitting mechanisms areengaged prior to gear shifting to achieve shifting without torqueinterruptions.
 8. The transmission defined in claim 2, wherein at leasttwo of said synchronizers comprise a double synchronizer to reduce costand package size.
 9. A multi-speed transmission comprising: an inputshaft; an output shaft; first, second, third and fourth planetary gearsets each having first, second and third members; a firstinterconnecting member continuously interconnecting said first member ofsaid first planetary gear set with said first member of said secondplanetary gear set; a second interconnecting member continuouslyinterconnecting said second member of said second planetary gear setwith said first member of said third planetary gear set, said firstmember of said fourth planetary gear set and said output shaft; a firstinput clutch selectively interconnecting said input shaft with saidsecond member of said first planetary gear set; a second input clutchselectively interconnecting said input shaft with said second member ofsaid third planetary gear set; and eight torque-transmitting mechanismsfor selectively interconnecting said members of said first, second,third or fourth planetary gear sets with said first or second inputclutch, with a stationary member or in pairs for common rotation, saideight torque-transmitting mechanisms and two input clutches beingengaged in combinations of at least three to establish at least sixforward speed ratios and a reverse speed ratio between said input shaftand said output shaft.
 10. The transmission defined in claim 9, whereinthe first of said eight torque-transmitting mechanisms is operable forselectively interconnecting said third member of said second planetarygear set with a member of said first planetary gear set, and the secondof said eight torque-transmitting mechanisms is operable for selectivelyinterconnecting said second member of said first planetary gear set withanother member of said first or second planetary gear sets, or with saidfirst input clutch.
 11. The transmission defined in claim 9, wherein thethird of said eight torque-transmitting mechanisms is operable forselectively interconnecting said third member of said third planetarygear set with said second member of said fourth planetary gear set, andthe fourth of said eight torque-transmitting mechanisms is operable forselectively interconnecting said third member of said third planetarygear set with said third member of said fourth planetary gear set. 12.The transmission defined in claim 9, wherein the fifth of said eighttorque-transmitting mechanisms is operable for selectivelyinterconnecting said first or third member of said first planetary gearset with said stationary member, and the sixth of said eighttorque-transmitting mechanisms is operable for selectivelyinterconnecting said third member of said first or second planetary gearset with said stationary member, said member interconnected with saidstationary member by said sixth torque-transmitting mechanism beingdifferent from said member interconnected with said stationary member bysaid fifth torque-transmitting mechanism.
 13. The transmission definedin claim 9, wherein the seventh of said eight torque-transmittingmechanisms is operable for selectively interconnecting said secondmember of said fourth planetary gear set with said stationary member,and the eighth of said eight torque-transmitting mechanisms is operablefor selectively interconnecting said third member of said fourthplanetary gear set with said stationary member.
 14. The transmissiondefined in claim 9, wherein planet carrier assembly members of aplurality of said planetary gear sets are single pinion carriers. 15.The transmission defined in claim 9, wherein planet carrier assemblymembers of a plurality of said planetary gear sets are double pinioncarriers.
 16. The transmission defined in claim 9, wherein each of saideight torque-transmitting mechanisms comprises a synchronizer.
 17. Thetransmission defined in claim 9, wherein said first input clutch isapplied for odd number speed ranges and said second input clutch isapplied for even number speed ranges.
 18. The transmission defined inclaim 9, wherein said first input clutch is applied for even numberspeed ranges and said second input clutch is applied for odd numberspeed ranges.
 19. The transmission defined in claim 9, wherein selectedones of said eight torque-transmitting mechanisms are engaged prior togear shifting to achieve shifting without torque interruptions.
 20. Amulti-speed transmission comprising: an input shaft; an output shaft;first, second, third and fourth planetary gear sets each having first,second and third members; a first interconnecting member continuouslyinterconnecting said first member of said first planetary gear set withsaid first member of said second planetary gear set; a secondinterconnecting member continuously interconnecting said second memberof said second planetary gear set with said first member of said thirdplanetary gear set, said first member of said fourth planetary gear setand said output shaft; a first input clutch selectively interconnectingsaid input shaft with said second member of said first planetary gearset; a second input clutch selectively interconnecting said input shaftwith said second member of said third planetary gear set; and seventorque-transmitting mechanisms for selectively interconnecting saidmembers of said first, second, third or fourth planetary gear sets withsaid first or second input clutch, with a stationary member or in pairsfor common rotation, said seven torque-transmitting mechanisms and twoinput clutches being engaged in combinations of at least three toestablish at least five forward speed ratios and a reverse speed ratiobetween said input shaft and said output shaft.
 21. The transmissiondefined in claim 20, wherein the first of said eight torque-transmittingmechanisms is operable for selectively interconnecting said third memberof said second planetary gear set with a member of said first planetarygear set, and the second of said seven torque-transmitting mechanisms isoperable for selectively interconnecting said second member of saidfirst planetary gear set with another member of said first or secondplanetary gear set, or with said first input clutch.
 22. Thetransmission defined in claim 20, wherein the third of said seventorque-transmitting mechanisms is operable for selectivelyinterconnecting said third member of said third planetary gear set withsaid second member of said fourth planetary gear set.
 23. Thetransmission defined in claim 20, wherein the fourth of said eighttorque-transmitting mechanisms is operable for selectivelyinterconnecting said first or third member of said first planetary gearset with said stationary member, and the fifth of said seventorque-transmitting mechanisms is operable for selectivelyinterconnecting said third member of said first or second planetary gearset with said stationary member, said member interconnected with saidstationary member by said fifth torque-transmitting mechanism beingdifferent from said member interconnected with said stationary member bysaid fourth torque-transmitting mechanism.
 24. The transmission definedin claim 20, wherein the sixth of said eight torque-transmittingmechanisms is operable for selectively interconnecting said secondmember of said fourth planetary gear set with said stationary member,and the seventh of said seven torque-transmitting mechanisms is operablefor selectively interconnecting said third member of said fourthplanetary gear set with said stationary member.
 25. The transmissiondefined in claim 20, wherein planet carrier assembly members of aplurality of said planetary gear sets are single pinion carriers. 26.The transmission defined in claim 20, wherein planet carrier assemblymembers of a plurality of said planetary gear sets are double pinioncarriers.
 27. The transmission defined in claim 20, wherein each of saidseven torque-transmitting mechanisms comprises a synchronizer.
 28. Thetransmission defined in claim 20, wherein said first input clutch isapplied for odd number speed ranges and said second input clutch isapplied for even number speed ranges.
 29. The transmission defined inclaim 20, wherein said first input clutch is applied for even numberspeed ranges and said second input clutch is applied for odd numberspeed ranges.
 30. The transmission defined in claim 20, wherein selectedones of said seven torque-transmitting mechanisms are engaged prior togear shifting to achieve shifting without torque interruptions.